Comments on: Wifi sometimes works, sometimes doesn't

Question: Wifi sometimes works, sometimes doesn't

Yiggs — Thu, 15 Mar 2007 18:59:15 -0800

Wifi acting odd... at the pub down the street I can always connect to the Wifi server, but half the time my browser times out trying to load anything, and nothing can connect. Half the time it works fine.

It says my connection is strong, and there's no obvious pattern why it doesn't work sometimes. When it doesn't work for me, it still works for everyone else. The pub owner has no idea, and nobody else seems to have this problem. I'm on a Powerbook with an Airport card, and can connect to servers elsewhere without a problem.

By: bshort

bshort — Thu, 15 Mar 2007 19:12:06 -0800

Are you not able to get to the router at all? Are you able to do a DNS lookup?

By: quin

quin — Thu, 15 Mar 2007 21:18:06 -0800

Yeah, DNS is my first guess as well. You are probably set up to use DHCP (which assigns you both your IP address and the DNS servers you use). I'd bet that the primary server you are getting is unreliable and it's timing out your browser before it has time to try the secondary.

If you go into your TCP/IP settings you can assign fixed DNS that your PC will use whenever you connect. Just enter the numbers you want to use in the Domain Name Servers box with a line break between them.

By: Yiggs

Yiggs — Thu, 15 Mar 2007 21:59:03 -0800

I'm able to connect to the router every time, and the signal is always pretty strong... I'm sorry, I'm not very technically literate, but how do I do a DNS lookup?

I checked and I am set up to use DHCP. Would I get the DNS numbers from the pub owner?

Thank you for the help!

By: Steven C. Den Beste

Steven C. Den Beste — Thu, 15 Mar 2007 22:27:31 -0800

"DNS" stands for "Dynamic Name Server". You do a DNS lookup every time you click a link with your browser if the link is given as text. For instance, if you enter "http://www.metafilter.com/" then your browser queries the DNS, which tells it that the IP is 70.86.84.162, the address the computer has to use with TCP/IP in order to reach www.metafilter.com.

If the DNS isn't answering, then you'll click a link or a shortcut and there will be a long pause (up to 30 seconds) while your computer waits for that translation response, after which you'll get an error message.

One way to see if it's a DNS problem is to actually use a direct IP. If "http://www.metafilter.com/" pauses, but "http://70.86.84.162/" doesn't, then the DNS is your problem.

By: quin

quin — Thu, 15 Mar 2007 22:56:35 -0800

If it helps, DNS servers aren't really regulated. You don't need to be logged into the ISP that is hosting them to use them.

In fact, I still use the one from the ISP I used to work for;

169.254.3.183

The company sucked after a while, but the servers are pretty solid.

By: Roach

Roach — Thu, 15 Mar 2007 23:12:33 -0800

Just to clarify SCDB's answer, DNS actually stands for "domain name system".

By: Roach

Roach — Thu, 15 Mar 2007 23:12:57 -0800

Or, Domain Name Server.

By: Steven C. Den Beste

Steven C. Den Beste — Thu, 15 Mar 2007 23:51:32 -0800

Some DNS's do refuse requests unless they're from an authorized bank of IPs.

By: datacenter refugee

datacenter refugee — Fri, 16 Mar 2007 01:29:54 -0800

Just guessing here but does the pub have 2.4ghz wireless security cameras? I just bought a bank of them and am having very similar serious packet loss issues. These would explain the random dropped connections.

By: Yiggs

Yiggs — Fri, 16 Mar 2007 08:46:24 -0800

Well, it certainly does seem like it is a DNS problem. I'll double check when it stops working next, but so far everything is pointing towards that.

Let me see if I have it all straight though... so the router has two DNSs, and I automatically connect to either one of them each time. One of them works fine, but the other causes me to time out for some reason. What I need to do is manually connect to the one DNS that works for me, which I can get from the pub owner.... is that all correct?

Oh, and no, there are no security cameras in the pub, but perhaps in one of the buildings next door... I'll check to be sure.

By: stovenator

stovenator — Fri, 16 Mar 2007 09:12:08 -0800

It could also be that you have an 802.11b adapter, while others are using 802.11G. It could be the antenna on your adapter. It could be somebody using the microwave. It could be a rogue Access Point pretending to be the pub's, in order to try to sniff/steal info. It could be any number of things.

As mentioned above, you will want to try things other than your browser, to narrow down the problem.

Things to try, that a Mac expert can tell you how to do from the terminal :

1. ping the router
2. ping the DNS nameserver
3. nslookup (DNS)
4. traceroute

Depending on the result of those troubleshooting steps, you could determine where the likely problem is.

By: quin

quin — Fri, 16 Mar 2007 09:46:36 -0800

Yiggs : Let me see if I have it all straight though... so the router has two DNSs, and I automatically connect to either one of them each time. One of them works fine, but the other causes me to time out for some reason. What I need to do is manually connect to the one DNS that works for me, which I can get from the pub owner.... is that all correct?

Sort of. The router does have two DNS numbers that it is supplying to you. A primary and an alternate, your computer will always try the primary first and if that fails, it will fall back to the other one. My thinking is that the primary one the router is providing you is unreliable.

I doubt the pub owner will know what DNS number to use, so my suggestion is to try putting in the one I mentioned upthread. It's pretty good. Alternatively find out what the ones are from the ISP you use when you are at home and use those.

By: jefficator

jefficator — Fri, 16 Mar 2007 12:11:34 -0800

I think have a similar problem: I have wi-fi in my apartment. Everytime I close my laptop, when I reopen it and attempt to connect to the internet, the connection fails. Trillian will still connect, however.

What gives?

By: stovenator

stovenator — Fri, 16 Mar 2007 13:45:13 -0800

and attempt to connect to the internet

I assume you mean "browse the web" ? You may want to start a different question, to avoid threadjacking.

By: Yiggs

Yiggs — Tue, 20 Mar 2007 19:26:12 -0800

Sorry it's been so long since I've responded, but it stopped working again and, as of right now, is my only internet source... so I can only really post about the problem when it is working properly!

Anyway, I had a chance to try out everything and it looks like it maybe isn't a DNS problem. First I tried using the DNS you gave me, quin. That didn't seem to change anything. Then I tried loading http://70.86.84.162/ instead of metafilter.com, and that just acted the same way - Firefox says "Looking up http://70.86.84.162/" for about 30 seconds, then times out.

I did notice one thing though - when it stopped working, it happened abruptly. I was connected fine, and then suddenly everything stopped working... I was still connected, but every link was timing out, and nothing could connect. Also, it stopped working for almost a week, no matter how many times I reconnected or rebooted.

So... I'm really not sure, this seems to be a very odd problem!

By: quin

quin — Tue, 20 Mar 2007 21:25:50 -0800

Sorry about that Yiggs. We'll figure it out yet.

Something I should have asked about before: are you running any firewall software? Specifically, and I'm assuming you are using XP, are you running any after-market programs like Norton, Zone-alarm, or MaCafee? I ask for two reasons; First, software firewalls are the source of all evil in the known universe when it comes to troubleshooting a connection problem. It is entirely possible that if you have one installed, that it is just randomly blocking all your connectivity. Second, Windows comes with it's own firewall, and if you have it and something installed after the fact both active, they could be conflicting with one another.

Here is what I would try next.

Turn off any and all firewall software. (The router you are behind should keep you protected well enough.)

Go to start-> run and type 'cmd' (without the quotes)
When the command window comes up type 'ping -t 17.254.3.183' and hit enter.
This is going to start an unending ping, leave this running in the background when you are browsing the web. When you seem to lose connectivity, check the command window and see if the pings have switched from 'Reply from...' to 'Request timed out'

What this will tell you is if in fact you are having a connectivity problem or if it's something else. Something in the browser perhaps.

If you need to, ctrl-c stops the ping command, or you can just close the window.

By: Yiggs

Yiggs — Wed, 21 Mar 2007 20:56:42 -0800

Ah, thanks quin! Unfortunately I'm on a Mac... I've got OS X 10.3.9, and as far as I know, no firewall software installed at all, let alone running. Do you know if OS X has a firewall running by default?

I'll try to find a ping command for OS X... I assume it would be the same deal? And then I'll wait until it stops working again to test it... thanks so much for the help so far though!

By: Yiggs

Yiggs — Wed, 21 Mar 2007 21:01:44 -0800

Ok, I figured out how to ping and it seems to be responding as it should, which only figures cause it's working fine. I'll have to see next time it goes down though. I'll let you know!

By: quin

quin — Wed, 21 Mar 2007 22:12:17 -0800

Sorry about that. I took a swing with the most common OS, looks like I missed. It's good that you figured out how to ping though, it is an invaluable tool when troubleshooting intermittent connectivity issues. (For the record, there are a couple of ways of pinging on a Mac. I'd advise using a terminal window for the trick I'm about to suggest. It's basically the same steps I outlined above, but you don't need the '-t').

The thought occurs that in addition to pinging an active internet connection, you may also want to test your connectivity to the router itself. This is very easy to do. Bring up your Network control panel

Apple -> System Preferences -> Network

And select Airport from the pull down menu called 'Show'. Then click on the TCP/IP tab. Here you will be presented with a bunch of information that will look something like this:

IP Address x.x.x.x
Subnet Mask 255.255.255.0
Router x.x.x.x.

The one we care about is the Router's IP address. My suggestion is that instead of bringing up a single Terminal window to ping apple.com (17.254.3.183) you should bring up two; one pinging apple's site, and one pinging the router itself. (just use 'ping x.x.x.x', where the x's are the IP address listed under TCP/IP.)

Why are we doing this? Because we are unsure where the connection is failing. If the window pinging apple fails, it's a problem with the router itself (unlikely as you have said that others don't seem to experience a problem), a more likely thing is that both will go down indicating that you are losing connection to the router itself.

Now there is firewall software in OSX, as I'm running an older version, I can't fully direct you to where to disable it, but it's usually off by default, so I wouldn't worry about it the same way I would on a Windows machine.

The good news is that Macs are very robust critters and the operating system is typically not a failure point. It might be something as simple as your web browser giving you grief. The bad news is that if it's not, it might be your wireless card. Which, in all honesty, isn't that hard to replace if it is the culprit.

Either way, the tests you are going to try next will bring you one step closer to an answer.

By: Yiggs

Yiggs — Thu, 22 Mar 2007 19:05:17 -0800

Ok, I didn't get your latest message before it went down last, but I will definitely try the two window pinging next. What I did do was just ping 17.254.3.183 when it wasn't working and this is what I got:

PING 17.254.3.183 (17.254.3.183): 56 data bytes
(then it stayed here for quite a while, doing nothing, but then it said...)
ping: sendto: No route to host
ping: wrote 17.254.3.183 64 chars, ret=-1

Over and over again... so I assume it wasn't working.

I will try your new test next time it goes down! (for the record: my wireless card is the old Airport card, not the Airport Extreme... I'm on a Powerbook G4, and I was told I can only use the old Airport cards.)

By: Yiggs

Yiggs — Fri, 23 Mar 2007 20:37:22 -0800

Alright... I pinged both the router and the Apple.com IP at the same time and the router responded perfectly, just like the other IP would do when my connection was working, but the Apple website IP did the same thing I described above... waited for a long time, and then gave the "No route to host" message. So do you think this means that the problem is with the router?

By: quin

quin — Sat, 24 Mar 2007 17:32:45 -0800

Unfortunately, I think this is the case. If you were able to talk with the router the whole time, then it's apparent that there isn't anything wrong with your wifi connection.

Honestly, I'm at a loss. Perhaps there is some weird proxy badness going on whereby you are being shunted by the router to a non-functioning connection. But I have no idea why others in the place wouldn't be complaining of the same thing.

I'll brood for a bit more on this one, but right now, I'm thinking it's an equipment thing on their side.

By: Yiggs

Yiggs — Mon, 26 Mar 2007 11:06:06 -0800

Hummm.... ok, well that's a bit discouraging. But thanks so much for your help! I'll keep trying different things, maybe something will finally work. Thank you!