LED TV breaking Wifi Network
December 27, 2013 11:05 AM   Subscribe

I have a wifi network on an Airport Extreme 802.11n, extended by several Airport Express (2008 model, MB321LL/A) base stations. My new Samsung LED TV, in a room about 20 feet from the Airport Extreme, takes down my entire network—I can't reach the internet anywhere in the house—until I shut down the TV and reboot the Extreme. Suggestions for diagnosing and repairing the problem, please?

My old plasma TV does not cause the same problem.

I have tried using different channels for the wifi network.

I have reset all routers.

I have moved the Extreme a few feet in one direction or another.

The Extreme is connected to a U-Verse DVR's ethernet jack. When the wifi network is down, I can still connect to the internet by disconnecting the ethernet cable from the Extreme and plugging it in to my laptop.

I have turned off every wireless setting I could find in the TV's settings.

I've thought about updating my Airport hardware (maybe newer models are more robust) or replacing the TV (maybe this particular unit is defectively shielded).

Any other great ideas?
posted by MarkWBennett to Technology (9 answers total) 1 user marked this as a favorite
Is the Samsung TV itself a WiFi client?
posted by Good Brain at 11:21 AM on December 27, 2013 [1 favorite]

Best answer: Can you post the model of the TV? Maybe we can look at the manual to see if any wireless features can be disabled.
posted by Blazecock Pileon at 11:26 AM on December 27, 2013 [1 favorite]

Could be that a fault in the TV is causing it to emit a *lot* of radio hash. This is probably making you very unpopular with your neighbours!

(It would also be grounds for returning the TV if true - consumer products are not permitted to put out that much radio interference.)
posted by pharm at 11:28 AM on December 27, 2013 [2 favorites]

Shouldn't the Extreme be connected to the u-Verse modem, and not the DVR?

I assume the TV is also connected to the DVR. Perhaps there's some sort of signal from the tv back to the DVR that somehow disconnects anything not in the authorized drm chain (or whatever it is they have in place to foil digital copying)?
posted by Thorzdad at 12:53 PM on December 27, 2013 [1 favorite]

Response by poster: The Samsung TV can be a wifi client, but I think I've turned that function off.

The TV is a UN46F5500AFXZA. The user manual is here: http://www.samsung.com/us/support/owners/product/UN46F5500AFXZA#

It could be a defective TV—improper internal shielding, for example.

U-Verse uses HPNA to share the internet connection through the DVRs' ethernet ports. I connect the Extreme there rather than to the modem because the modem is on the margin and the DVR is in the center of the house.

Your signal-back-to-the-DVR theory had me going until I recalled that the problem persists when the TV is connected to the XBox, or to nothing at all.
posted by MarkWBennett at 1:00 PM on December 27, 2013

Something else to check - is there a chance that the TV is hard-set (or manually configured) with an IP address that's clashing with the router?
posted by jquinby at 2:15 PM on December 27, 2013 [1 favorite]

Response by poster: While all of the answers were helpful to me, because they led to the solution, I've marked Blazecock Pileon's as the best.

The solution was to connect the TV to the network via ethernet cable. This done, the interference ceased.

My theory is that even though I had switched WiFi off as much as it could be switched off, until it had a wireless connection the TV was still trying to make a wireless connection, which for some reason was breaking the network.

Thank you all. Now my kids can play XBox without cutting off our connection to the outside world.
posted by MarkWBennett at 2:35 PM on December 27, 2013 [1 favorite]

It could be a defective TV—improper internal shielding, for example ... I recalled that the problem persists when the TV is connected to the XBox, or to nothing at all.

I'm voting this, as in "defective TV". I've seen and heard of multiple sound bars and recent TVs causing interference like this that breaks wifi. Something is letting out hoards of EMI in the LED driver board, and probably the scanning backlight controller in the TV if it's a nice enough samsung to have smart functionality.

See, the backlights are driven by PWM, which is to say there's a constant high frequency signal causing them to flicker to create a specific not-full-power brightness. The backlight also needs to be driven by constant current, not constant voltage. The current load for a given voltage changes as the TV warms up and cools down due to changes in resistance/impedance in the LEDs and the driver circuitry causing efficiency to rise and fall.

In addition to this, on many modern TVs like most samsungs that advertise "240 clear motion rate!" or even higher, the actual panel in the tv is 60hz, or 120 if it's a nicer tv or 3D. Only very expensive tvs have real 240hz panels, and even those when they're samsungs still have a scanning backlight to give the illusion of an even higher refresh rate in the 720-900something hz range.

Where i'm going with that, is this requires a different and even more complex system that's shooting around lots of high frequency signals to pulse the backlights rhythmically at a very high rate down the display, in addition to keeping the various areas of them lit to a different never-full-voltage level.

So, you have all this stuff farting out lots of high frequencies with relatively quite a bit of power. Not half a watt or something, tens of watts. even over 100. And since this isn't a military satellite, there's lots of broadband noise and other garbage signal flying around in there probably.

So, if any of that system has damage to it's shielding, or is slightly grounding out on any metal shielding piece inside the chassis or something(or jumping a tiny gap in a crappy solder joint, maybe ONE led in the backlight you wouldn't even notice isn't lighting quite as bright?) then you're now spewing out tons of high frequency EMI.

See this sort of thing. You're unintentionally creating that kind of interference. Either through an actual gap, or through something that's supposed to be a shield not being properly mounted or acting as a makeshift transmitter.

I would honestly replace the TV before i'd bother with anything else. "TV on and not connected to anything = interference and network failure" points very strongly to defective TV and not much else.

Personally i'd call samsung support and explain the problem, and really hoop and holler and whine and comment how your airport doesn't even work even if you unplug the TV after it has caused the interference, and that you're worried it may have damaged other equipment in your house(you know, ignoring the part that rebooting it brings it back up. ham it up). I'd use this to try and get a fancier model as a replacement from them to clam up about the TV screwing up your stuff, but i'm also an asshole. An asshole who, however, would feel fairly justified in that kind of chicanery if i had spent $1k or so on a TV that was now causing these types of problems.
posted by emptythought at 2:35 PM on December 27, 2013

Make sure you have SWL (Samsung Wireless link) turned off. I believe I had similar problems when I installed my TV originally. I think SWL allows the TV to connect directly to Samsung phones wirelessly without the need for a WiFi network...If I remember correctly it doesn't play nice with existing wireless networks.

Not sure why going wired fixed your problem, but take a look at the SWL setting...
posted by NoDef at 4:24 PM on December 27, 2013

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