Moving between Wifi
June 5, 2020 8:59 AM   Subscribe

I've got a router in the front of the boat and relay in the back of the boat. My phone can see both, but not well enough to actually get data. How can I get my phone to drop the other wifi when it's closer to one that actually works?

If I move from the front of the boat to the back my phone will stay connected to the main wifi, but will not be able to actually send any data, so it is, essentially, unconnected.

The back cabin router is connected via an ethernet cable to the main router.
posted by Just this guy, y'know to Technology (26 answers total) 4 users marked this as a favorite
 
Given that you've done the right thing with Ethernet wiring from front to back, the right way to deal with this is by using enterprise-grade wireless access points specifically designed to deal smoothly with frequent handoffs. Ubiquiti's UniFi line is the most cost-effective option I'm aware of in this space. Setting these up requires the use of UniFi Network Controller software, but after they've been set up they'll happily run on their own.
posted by flabdablet at 9:46 AM on June 5, 2020 [1 favorite]


Professional network guy here and sad to report that you're kind of screwed as that decision (which AP to connect to) is made by the client (your phone) and they don't typically include options to tune that kind of thing.

I believe your best bet would be a mesh system where the APs can coordinate with one another. If they can do that then they have options to push the client to an AP with a better signal.

This is essentially the same answer that flabdablet has posted. I have Ubiquiti's Amplifi system which is the consumer version of UniFi. I'm happy with it from a performance standpoint. I do wish I'd gone with UniFi instead but that's largely because I do this stuff for a living and I'd like to have all the secret knobs to tweak. AmpliFi's interface is pretty simple and is only available on a phone (and that's the part I really don't like, same thing with a web interface and I'd be okay).

Search for mesh wifi and you'll find lots of options.
posted by Awfki at 9:51 AM on June 5, 2020 [4 favorites]


Mesh wifi is good when you need your access points to talk to each other over wireless as well as to clients; it's not really appropriate for a simple setup with a cable between the two APs.

Before spending any money on doing things right, though, you might want to try the sticky tape and string approach and use something like Wifi Roaming Fix to make your phone a bit more aggressive about finding good signal. Just make sure that your access points are both set up with the same SSID, both using WPA2 with the same passphrase, and working on different and non-overlapping wifi channels.
posted by flabdablet at 9:57 AM on June 5, 2020 [5 favorites]


Oh, and both access points will want to be connecting clients to the same IP subnet as well. If the thing in the back of the boat is currently configured as a NAT router, put it in "bridge" mode to turn its router brains off and leave all the routing to the one in front.
posted by flabdablet at 10:09 AM on June 5, 2020 [2 favorites]


Probably a dumb question/answer, but would a single router in the middle of the boat cover the whole thing? Or are the current router and relay located at quarter points along the boat's length, rather than at the very ends?
posted by jon1270 at 12:14 PM on June 5, 2020 [1 favorite]


The chipset in your AP almost certainly supports disconnecting clients that fall below a certain signal strength, but the necessary configuration knobs are not exposed in consumer software.

You might check to see if there is third party firmware available for one or both of your boxes. As long as one of them is configured properly it should be enough to do what you need.

Mikrotik sells some very low cost APs that will do the trick if you need a new device. After setting it up as an AP using the simple configurator, you would only need to tweak one or two settings on the wireless interface manually, so the complexity of the underlying system shouldn't present a problem for you.
posted by wierdo at 12:25 PM on June 5, 2020 [2 favorites]


How big is your boat that you have two 'routers' and you can't get signal from one end to the other and are using multiple 'routers' to cover you giant boat.

Iff you're using off the shelf consumer plug-and-play router-with-wifi plugged into each other... that's wrong. But doable.

You need ONE router with WiFi for the front, the cable to the back, and the second device needs to be in bridge mode (NOT A ROUTER) and both need the same SSID/password/etc.

Otherwise with two routers with WiFi (that you didn't configure) the back of the boat will be on a different DHCP allocation and your phone will prefer to keep the front connection.

Unless your boat is ginourmous you don't need two 'routers' and if you're using router-WiFi-combo things without tweaking the config..... You will have what you describe as a failure to roam because your phone doesn't want to switch networks.

flabdablet is right. Ignore all of the mesh network stuff. I'm a 15 year veteran of deploying wired and wireless among random buildings in a university environment. (how big is your boat? I'm having a hard time thinking that you can't get signal with a single WiFi AP).
posted by zengargoyle at 10:10 PM on June 5, 2020 [2 favorites]


To clarify, the boat is made of steel.
Wifi Signals don't go through steel plate very well. It's (21 metres long, but the main router is in the hold and the rear router is in the aft cabin, which is it's own steel structure.)
I'm using routers as a generic term. I don't know if its necessarily correct. (I assume not)

Currently the main router is a huawei 4g/5g gigacube thing and the back cabin one is a tp-link ac750 router.
So the internet comes in to the gigacube and then goes down the wire to the tp-link

I like the sound of this bridge business.
I will look into the configuration of the back cabin router/thing/box...
posted by Just this guy, y'know at 3:28 AM on June 6, 2020


What are the exact model numbers of the devices you have?

I know that TP-Link makes things they call "range extenders" and these are designed to connect via wifi to an upstream access point. They can be made to work as plain wireless access points, but that's not how they come configured out of the box.

If you've got one of those, and it's in extender mode, and you've got its wired port connected via Ethernet cable to a LAN port on your main router, I don't imagine it would do what you expect. In extender mode, the LAN port is there to provide a way for things that have only wired interfaces to get connected to a Wifi network, which is the exact opposite of your present use case.

I'd try shutting the main router down, then connecting to the config page on the TP-Link extender, flipping it into WAP mode, then rebooting the TP-Link, then starting the main router back up and see where I was at.

If you try this, and it doesn't work, and you find you've also mysteriously lost all ability to get to the TP-Link device's admin page, post back and we'll troubleshoot.
posted by flabdablet at 5:19 AM on June 6, 2020


Right. There are a bunch of settings here which are a bit confusing. But I think I have something.

Oh. My laptop seems happy enough (though I still have tests to run) but my phone seems unhappy with the password situation.
Also it seems like once I change the settings to act as a bridge I can then not log back into the management console of the router except by rebooting the thing.
So something is right and something is not.

Still... promising.
posted by Just this guy, y'know at 5:51 AM on June 6, 2020


Model numbers, please.
posted by flabdablet at 6:08 AM on June 6, 2020 [1 favorite]


Shoulda previewed.

The TP-Link device is an archer c20i.
I think the main router is a Huawei Gigacube B528s-23a

I've disabled DHCP on the TP-Link and set the 2.4Ghz Wifi connection to WSD mode and linked it to the main device.
I've given this the same SSID as the main device.
There are some NAT options that I feel like I should do something with, but for now have left alone.

I'm now connected to the Wifi in the back cabin with full signal strength. So I assume it's working.
I'll go see if it retains full strength in the main room....
I have moved to the other end of the boat and I do seem to have signal.
Now all the way back. Laptop remains happily connected throughout.

So, here's the oddity.
My phone won't connect in the back cabin.
The laptop is happy in both places. The phone is only happy in the front of the boat.
In the back it gives me an authentication error.

I can't connect to the admin page of the Tp-Link any more.
I assume that's because the main router wants to be 192.168.0.1 (or whatever) so the TP-Link needs to be somewhere else.
posted by Just this guy, y'know at 6:10 AM on June 6, 2020


OK. I now have a user manual for the TP-Link Archer C20 but am having trouble finding one for the Gigacube.

Could you shut down the TP-Link box, connect to the admin page on the Gigacube, find the DHCP Server settings, take a screenshot, stick it up on imgur and post a link?
posted by flabdablet at 6:22 AM on June 6, 2020


I've disabled DHCP on the TP-Link and set the 2.4Ghz Wifi connection to WSD mode and linked it to the main device.

I think that's probably the Wrong Thing, partly because I can find no mention of a WSD mode in the manual but mostly because the TP-Link should not, to my way of thinking, have a wifi link to the Gigacube. The TP-Link should be in Access Point mode - see page 15 (PDF page 20) and Chapter 5 (PDF pages 73ff) and its only link to the Gigacube should be via the Ethernet cable.
posted by flabdablet at 6:29 AM on June 6, 2020


I can!
Though not for a bit because I've had to head out. But I will do so as soon as I get back in.

Thanks for all your help so far guys
posted by Just this guy, y'know at 6:30 AM on June 6, 2020


The pathway I have in mind goes like this:
  1. Factory reset the TP-Link box so we can get to its admin page again.
  2. Find out what IP address range the Gigacube is using, and restrict its DHCP server to handing out device addresses only between 100..199 inside that range.
  3. Verify that the Gigacube's own admin page has an IP address that ends with .1. I suspect it will turn out to be 192.168.5.1 but the DHCP screenshot you're going to post will tell me for sure.
  4. Turn the Gigacube off, turn the TP-Link on, and connect to its admin page.
  5. Put the TP-Link in Access Point mode (see manual page 71).
  6. Set the TP-Link's LAN Type to Static IP, its IP Address to (probably) 192.168.5.2, its Subnet Mask to 255.255.255.0 and its Gateway Address to (probably) 192.168.5.1 (we want the TP-Link to be using the Gigacube for its gateway).
  7. Restart the TP-Link. Make sure it's still showing up on lists of available wireless networks with its own factory default SSID, connect via Wifi to that SSID, make sure we can now open to its admin page at the new address.
  8. Disable the TP-Link box's DHCP server.
  9. Turn the Gigacube back on.
  10. Go to a spot on the boat where the Wifi signal from the Gigacube works well, connect to the Gigacube's SSID, and verify that we can still connect to the TP-Link admin page via (probably) http://192.168.5.2; the http://tplinkwifi.net convenience name will most likely no longer work at this point. If that works, it proves that the Ethernet link between the Gigacube and the TP-Link is now functioning.
  11. Go to a spot on the boat where the Wifi signal from the TP-Link works well, connect to the TP-Link SSID, and verify that we can still connect to the Gigacube's admin page at 192.168.5.1. If so, that proves that the Gigacube's DHCP server is now able to assign addresses to TP-Link connected devices, which is most of the point of having got the thing into Access Point mode to begin with.
  12. Alter the SSID and WPA2 settings in the TP-Link's admin page so that they match those on the Gigacube.
  13. Margaritas on the deck.

posted by flabdablet at 6:56 AM on June 6, 2020 [1 favorite]


By the way, if you're thinking it shouldn't require an involved and intricate 13-step process just to put two WAPs on a boat and have them work properly: you're completely correct. TCP/IP sucks.
posted by flabdablet at 7:59 AM on June 6, 2020 [1 favorite]


Here is the Huawei DHCP page:
It's a H112-370 incidentally

https://imgur.com/a/GXn9IOy
posted by Just this guy, y'know at 8:50 AM on June 6, 2020


I've taken a picture of the exciting 13 point plan and will see what I can do about implementing it.

1. I have restricted the DHCP range of the gigacube to 192.168.8.(100 - 199)
2. The gigacube's IP is 192.168.8.1
3. I turned OFF the gigacube. (I then realised I couldn't post this with it off and plugged it in again. But I will turn it off once I've posted this and will go into the back cabin to do step 5

...
posted by Just this guy, y'know at 8:56 AM on June 6, 2020


I think....
It works?

I couldn't access the manual, because TP-Link's website loves to redirect. I searched for Archer C20 Access Point Mode and it gave instructions which could not be followed. (The menu items literally did not exist).

Further searching directed me to this. That seemed to be saying very similar things things to what you were saying.
So I merged both bits of advice.

I am in the back cabin with the steel hatches closed and have full signal.
I can also access admin pages for both routers.
I can't say I 100% understand what it all means. But it works!
Woooo!

It's currently a bit drizzly here and I'm supposed to be supervising children playing in the woods so I have substituted step 13 with "Drink a Dark 'n' Stormy in the woods"

Thanks so much!
posted by Just this guy, y'know at 9:27 AM on June 6, 2020 [1 favorite]


The gigacube's IP is 192.168.8.1

Then just substitute 192.168.8 everywhere you see 192.168.5 in the plan and it should work.
posted by flabdablet at 9:28 AM on June 6, 2020 [1 favorite]


Now it's me who should have previewed.

Well played! Glad you got a result.

I can't say I 100% understand what it all means.

Let me see if I can get you to 90%.

Network protocols are best thought of as being layered, where the design of each layer takes care of one specific set of concerns and leaves other concerns to the other layers.

With perfect layering, you could switch out all the layers lower than any given layer and the given layer would still work; furthermore, your switching-out would remain completely invisible to layers above the given layer. It's not quite that clean in practice but it gets pretty close. Think of how you can put concrete or particleboard or steel deck plate under a wall to wall carpet, and not need to care which of them is underneath in order to know which attachment to use to vacuum the floor, and you'll get the gist.

Layer 1, the physical layer, is the most fundamental. The concerns of Layer 1 are turning some kind of signal transferred through some kind of medium into digital bits and back. Inside your boat's local network you're running two Layer 1 protocols, 802.3ab signalling over your Ethernet cabling and 802.11ac signalling over 2.4GHz and 5GHz radios.

Layer 2, the data link layer, concerns itself with how digital bits get assembled into packets and how those packets get presented to the physical layer for exchange amongst directly connected local devices. On your boat you're running one data link layer protocol, 802.3 (aka Ethernet), over your two physical layers.

Data packets on the boat can get transferred directly between any two devices whose data link layers can see each other. The Gigacube box will have a network switch inside it that copies Layer 2 packets back and forth between any of the wired LAN ports and the Wifi radios; in Access Point mode, the TP-Link box's wired port and radios will work similarly.

Layer 3, the network layer, concerns itself with how packets get exchanged with computers everywhere, not just on local networks. Most of the Internet runs on the same Layer 3 protocol: Internet Protocol or IP.

When your phone wants to send an IP packet to e.g. one of Google's servers, its internal IP layer knows that Google's servers don't exist inside your phone or even on your boat; so it builds an IP packet and hands it over to the data link layer for delivery to your local gateway, a Layer 3 router. The router, in turn, sends it off to some other router upstream of its own WAN connection. It also arranges to collect any replies to that packet and hand them back, via the data link layer running on one of its LAN ports or radios, to your phone.

What you used to have in the back cabin was a second Layer 3 router. Effectively, the rest of your boat was acting like an Internet Service Provider for the cabin; devices connecting to the TP-Link wifi could not see its wired port's data link layer, or any of the devices connected to that layer, directly. Everything connected to the wired port, from the cabin's point of view, was Out There In The Cloud.

Moving your phone from the cabin to anywhere else was analogous to walking entirely out of your house and going over to the neighbour's; the phone was told that it needed a new IP address when it got there, because it wasn't on the same local network as it used to be in the cabin so its old IP address was of no use to it.

That kind of IP address switching is highly disruptive to ongoing traffic (did I mention that TCP/IP sucks?) so it's something the phone will tend to resist doing until it perceives absolutely no choice.

By switching the TP-Link box in the cabin to WAP mode, you've made it so that any device anywhere on the boat can talk to any other using layers 1 and 2 only. They'll use Layer 3 anyway because everything does, but all the Layer-3-specific concerns - in particular, the assignment of a Layer 3 IP address - are swept under the carpet and made invisible at Layers 3 and above. That means your phone is free to choose the best signal it can find without having the Layer 3 rug pulled out from underneath everything that was using it.

Any local network whose devices can all talk to each other on Layer 2 needs only one DHCP server operating on it to manage automatic assignment of Layer 3 IP addresses. Running more than one invites IP address collisions and general mayhem. This is why the TP-Link's DHCP server needed to be switched off; there's already one in the Gigacube.

And configuring 192.168.8.1 and 192.168.8.2 as static IP addresses of the Gigacube and TP-Link admin interfaces, respectively, means that both of those interfaces have stable, well-known IP addresses that conflict neither with each other nor with those of any of the DHCP-managed devices that will come and go on the LAN, each of which will be assigned its own address in the range from 192.168.8.100 through 192.168.8.199.

If you put a printer on this boat, connect it to a wired port on the Gigacube and configure it with a static IP address of 192.168.8.3. That way, Windows in particular won't spit the dummy and want its driver reinstalled every other week.
posted by flabdablet at 10:29 AM on June 6, 2020 [1 favorite]


all the Layer-3-specific concerns - in particular, the assignment of a Layer 3 IP address - are swept under the carpet and made invisible at Layers 3 and above.

Just to be clear: what this means for you, specifically, is that once a network interface on some device has been handed an IP address by your boat's sole remaining DHCP server, that same IP address will continue to work for that device anywhere on the boat regardless of which wifi radio it's actually talking to or which LAN port it's wired through.

And if for some reason you want more wired ports, don't get them by adding another router; use simple plug-and-play desktop Ethernet switches, which work at Layer 2 with no need for configuration.
posted by flabdablet at 10:57 AM on June 6, 2020 [1 favorite]


In particular, you could get more wired ports in the cabin by inserting one of those switches between the cable to the hold and the TP-Link WAP, and the WAP wouldn't even notice you'd done that. Or you could connect it to one of the TP-Link's LAN ports. Either way would work.
posted by flabdablet at 11:03 AM on June 6, 2020 [1 favorite]


Darn, I missed all the fun by going to bed. Glad things worked out.
posted by zengargoyle at 12:04 PM on June 6, 2020 [2 favorites]


Final (hopefully) thoughts: just noticed that I recommended attaching any future printer to a wired port on the Gigacube specifically. I wrote that while harbouring an incorrect assumption that the TP-Link didn't have any spare wired LAN ports of its own.

Knowing now that it does, let me reassure you that the way things are connected and set up now, all of the currently unused wired LAN ports on Gigacube and TP-Link boxes are functionally interchangeable; anything needing a wired connection to the boat network can get plugged into any of them and will Just Work.

If you need more wired outlets anywhere on the boat, running a single Ethernet cable into the compartment concerned will be plenty good enough. The upstream end of that cable can go to any of your existing wired LAN ports. Pick the existing port on the basis of wiring being easy to get to it rather than anything else. If you're short of ports in any compartment, add a desktop switch there.

Just make sure there's only one way for a packet to find its way from any switch (including those inbuilt in the Gigacube and TP-Link boxes) to any other; you don't want to create closed loops in your network for packets to chase their tails around. In theory the Spanning Tree Protocol built into the switches and WAPs will stop that from happening by automatically disabling redundant paths, but troubleshooting becomes much easier if you know for sure which cable any given packet would have to use to get from A to B.

Also in theory it's nicer to organize your wiring and your switches in a way that minimizes the number of switches any given packet will have to find its way through as it transits the most commonly used pathways on your network, but with gigabit Ethernet linking fewer than hundreds of ports you're never going to see a measurable improvement from worrying about that.

And if you've got networked equipment on your boat that doesn't need to be portable, I'd strongly encourage you to use wire rather than Wifi to get it networked. Wires have such nice simple predictable failure modes, most of which can be identified with a multimeter and a magnifying glass. When Wifi doesn't work it can be a bastard to figure out why.
posted by flabdablet at 10:05 PM on June 6, 2020 [1 favorite]


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