My bedroom doorway is a nearly complete barrier to my wifi network. Why?
February 8, 2017 12:43 AM   Subscribe

If I walk around my house carrying my laptop and running speedtest.net over and over, my download speed is between 180 and 225 Mbps. I get the lower speeds when standing in the limestone shower, and the higher speeds almost everywhere else. But when I walk into my bedroom, the speed drops to 1.3, 1.1, if I'm lucky, 2.0 Mbps (yes, two). And inside the bedroom it's the same low speed. The speed drops almost the instant when I step into the doorway, meaning the door is open. WTF?

I've tested the following things:

This doesn't happen in any other doorway in the house, or any other room.

Above the bedroom doorway are an old wired-in smoke detector (disabled, no battery in it) and a wifi-enabled Nest Protect. Neither of those devices, singly or together, cause any drop in speed in the other places in the house where I can test them. I've disabled the Nest too. No improvement. (It's re-enabled. I should be protected from fire.)

The speed drops exactly the same way after I've unplugged the powerstrip in my bedroom that powers the bedside lamp, the lava lamp, and the electric blanket. And again when I plug it back in and turn everything on.

The speed is low on the bed, on the floor, in the air. It's low with the laptop sitting on a windowsill, sitting on a shelf; with me touching the laptop, with me not touching it, with me in the room, with me standing just outside the room watching the speed test on the monitor, with another person in the room with me, and without. With the lights on, and off.

I've added an Apple Airport extender to my network and placed it just outside the room. No improvement. Just inside the room. Sitting right in the middle of the doorway (oh, that's convenient). With its electric cord wrapped around the cord to the electric blanket. With it in another room, sitting in the window facing a window in my bedroom, so I can see the Airport from my bedroom window, but it's in another room in the house. With my iPhone in the room, and with it banished outside. Same phenomenon.

My house is pretty much out in the country. I have neighbors on each side with networks, and an xfinity public hotspot nearby. I don't live in an apartment building with two dozen networks nearby. My house is pretty big, but it's really open. It was built in 2000.

There are other wifi networks around, and I've got four myself: dual channels, home and guest. I've tried turning off three of the networks and just using the 5 GHz network. No improvement. I've tried using the 2.4GHz. Nothing.

To make things even stranger, I've had this problem on and off for years. Tonight was the first time I tested everything, obsessively walking around the house carrying my laptop, so I can't be sure it was the same, exactly, in the past. I haven't been able to watch movies in bed reliably — but I have been able to watch them sometimes, and they stream better if the door is open. And just now I tested it again, and the speed never dropped below 75. It was 220 outside the room, then 140 in the doorway, then 90 in bed, slowly dropping to 77, which is what I'd expect from normal attenuation. All the testing I did was when no one else was doing anything in the house, so I can't point fingers at, e.g., a microwave.

I have not tried wearing a tinfoil hat, but I'm running out of better ideas.

Any suggestions for what else could be causing my doorway to be an absolute barrier to wifi — sometimes? It's not the door, it's the doorway. Is there something that the contractors might have put around the door frame, inside the walls, that would block so much of the wifi? And if so, why? And what could be turning it on and off?
posted by Capri to Technology (18 answers total) 5 users marked this as a favorite
 
Does the bedroom have plaster walls? Are major pipes or a chimney between the bedroom and the wifi?
posted by zippy at 12:49 AM on February 8, 2017


Did you connect the Airport to your home network by ethernet cable, or was it just acting in wifi repeater mode? Because if the latter, it’s going to suffer from the same problem that your laptop does. If you want to guarantee a decent wifi signal you need a wired access point in your bedroom.

As to why this is happening: You might have chicken wire in the walls, turning your bedroom into a Faraday cage? Combine with an occasional electrical fault that spat out broadband radio noise & that would fit the symptoms.
posted by pharm at 1:22 AM on February 8, 2017 [7 favorites]


You did not request an alternative, but I suggest a Powerline Adapter. This uses the electrical grid in your home to allow you to connect via ethernet or to plug in another router within the bedroom. It works.
posted by yclipse at 4:36 AM on February 8, 2017 [1 favorite]


You might be able to track it better using an app like wifi analyzer on your phone, which will give instant signal strength updates as you walk around.
posted by scodger at 5:26 AM on February 8, 2017 [4 favorites]


I like scodger's idea of doing some detective work with a different device. It would at least confirm if the problem is unique to the laptop or not.

If not too inconvenient, I would experiment by putting the Airport outside the bedroom door with a clear view to the laptop inside. One would expect that to work OK, so if it doesn't then you know the ordinary sort of explanation is going to fly.

I'm not a tech guy, but I did work in an office that was networked via wifi instead of ethernet. Our IT guys discovered that the modem would drop to the speed of the lowest speed device it was connected to.

So far, I'm leaning to the "metal in the wall" explanation.
posted by SemiSalt at 6:19 AM on February 8, 2017


Metal in the wall is a good idea - it could be metal lath like this, which was used before drywall / sheetrock became ubiquitous. Your whole room could be a Faraday cage!
posted by Quietgal at 6:32 AM on February 8, 2017 [1 favorite]


To those focusing on metal lath: the OP mentions the house was built in 2000. You can still buy metal lath for plastering as Quietgal's link indicated, but it would be unusual to have it only in that one wall and not elsewhere in the house.
posted by beagle at 7:41 AM on February 8, 2017 [1 favorite]


I didn't see you mention changing the wifi channel on the network. Perhaps your channel is matching with the neighboring networks at that particular point?
posted by JoeZydeco at 7:44 AM on February 8, 2017


Yeah, I'd put WiFi Analyzer on an Android phone or tablet (or find an equivalent for other platforms) and see if you've got channel interference in that room.

Other possibility: Something in the paint in that room acting as a Faraday cage?
posted by straw at 8:20 AM on February 8, 2017


This is fading causing a low RSSI and high Packet Error Rate and corresponding rate down selection from the AP.

The cause of the fading is something to do with the geometry and physical construction of your house. The only easy way to change the fading is to reposition the AP until conditions improve.

I would enable greenfield (turn off a,b,g support) on the AP. This will disable the very low speed rates and force the AP to fall back to 6Mbits.

Try forgetting either the 2.4GHz SSID or 5GHz SSID on the laptop and see which frequency gives you the best throughput. It should be the 2.4, but who knows.

If you do NOT have an 802.11ac AP and have an 802.11ac laptop then it may be worth upgrading the AP due to beam steering support on the AP side.
posted by pdoege at 9:09 AM on February 8, 2017 [1 favorite]


These are all great ideas ... but they're missing one key symptom: the dropoff doesn't always happen. It either drops off to almost zero, or it drops off normally (i.e. from 225 to between 85 and 125). There's something that turns on that causes interference right in that doorway. So, my room is not a Faraday cage (although that sounds rather interesting after a glass of wine).

If there's something in the walls (which makes sense) that's causing this, it's something that's affected by something turning on and off. That room is in the corner of the house, and not much connects to it. To one side is a dressing room (nothing electronic in there) and to the other is the bathroom. Could it be related to the furnace? The bathroom floors have radiant heat; the rest of that floor isn't heated, as it's open to the main floor, and the heat drifts up from there (hence the electric blanket in the one part of the upstairs that is behind a door). The furnace is as far away from that room as possible, but could there be a switch for the radiant heat in the bathroom floor that turns on / off and interrupts the wifi through something in the floor under the doorway?

I'll see what happens if I set the wifi to fixed channels and move them around; it's on auto right now. Does channel sharing really drop the signal that much? Seems too radical a drop. Maybe what's turning on and off is outside the house, although the absolute drop at the doorway and no where else suggests not.

I've tried putting the wifi extender in the hallway and connecting from two feet away in the bedroom. The doorway acts as a near-complete barrier to wifi in that position, even with the door open.

There's no feasible way to hardwire my bedroom. If I can't solve this puzzle (which I really want to do) I'll buy the power line adapter yclipse recommended. The Comcast tech recommended that too (when he didn't feel like trouble shooting a different problem).
posted by Capri at 9:29 AM on February 8, 2017


Re intermittent problems, is it possible you have an electrical device near the bedroom giving off RF? Dimmer switch, microwave, furnace (the blower motor), or perhaps the electric blanket?

Or is one of your neighbors a ham radio operator?
posted by zippy at 9:32 AM on February 8, 2017


The AP's rate selection is going to look at RSSI and PER and choose a rate.

If you have multiple devices and beacons (eg. multiple guest SSIDs, etc.) then you can have channel congestion that forces the PER up. When you enter a room with lower RSSI the AP will down select. This will cause more channel congestion. Which will drive PER up. Which will cause down selection. Eventually the AP will drop to 1Mbit and stay there.

Turning off A,B,G gets rid of the really low rates and masks the problem.

Why does it happen sometimes? If the triggering condition (congestion and RSSI due to fading) never occurs then the AP will stay at a high rate and all is well.

You can test this by rebooting the AP when the problem occurs. If the rate (you would see this as throughput) starts out well after a reboot then my explanation is correct.
posted by pdoege at 9:43 AM on February 8, 2017 [1 favorite]


Do you have electric or hot water radiant heat? Either way, it's possible that the mesh or heat spreader plates might also be generating a faraday cage of sorts.
posted by suedehead at 10:41 AM on February 8, 2017


Plenty of good advice in this thread, I just wanted to add one thing:

If you have a Macbook (a reasonable assumption since you're using an Airport), there's a pretty handy "Wireless Diagnostics" app built into OSX that lets you monitor signal strength. When you load it, there's a wizard that pops up, but you can totally ignore the wizard and pick "Performance" from the "Window" menu. This gives you a graph of signal/noise strength. There are some other handy features there too (channel scan, etc).
posted by neckro23 at 10:45 AM on February 8, 2017


Have you had anyone else, with the same and/or a different laptop/smartphone, confirm your measurements? The problem sounds very odd if you can sit in the bedroom, within sight of the AP and have almost no signal. Fascinating!
posted by julianb at 2:47 PM on February 8, 2017


A long shot but... What does it have in it's pocketses?

A bad connector can let cellphone signals into the cable modem system and cause your cable modem to glitch. If you are doing these tests with your cellphone in your pocket and your cellphone is transmitting, and if your doorway just happens to be near the bad wire/connector, then every time you walk by it will cause trouble.
posted by soylent00FF00 at 6:17 PM on February 8, 2017


So many theories to test! Thanks all. I'm going to be busy for a while :)
posted by Capri at 6:46 AM on February 10, 2017


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