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Old 05-14-2019, 09:29 PM
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4-Second Wi-Fi Apocalypse


I realize my home Wi-Fi isn't what you'd call robust. I have plenty of speed, but my wi-fi-analyzer app shows my area is crowded with home networks, and I'm onthe best available frequency in either band. And, when I'm in the right spots, my garage door opener and microwave trash my signal. But my cell signal isn't particularly good here, so overall, I'm cool.

I got pinged on my phone that an update was available. I'm sitting directly next to my router, and the not-that-old router is directly next to a TV (We have joint cable/internet and, because it's basically free, a land line.) I clicked to accept the update, which lasted, by my count, four seconds. During that four seconds my TV reception went to hell. The instant the download ended, the TV cleared up.

Help me troubleshoot. TV, cable box, router, modem, phone, something else entirely? Is everything on the verge of melting down? Is it hey, stuff happens?

Help me. . . please.
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Old 05-14-2019, 09:37 PM
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TV?
A smart TV?
Connected to the router you just did a firmware upgrade to?
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Old 05-15-2019, 08:24 AM
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I don't think it's smart, I know it doesn't give me much in the way of options. Connect Ed to the cable box by HDMI. Only other input is an OTA antenna. Don't know when anything's firmware was updated. I think I bought the router in the last 12 months.
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Old 05-15-2019, 07:27 PM
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Wow, can't believe no one can point me in a direction. I'm going to bump this one time, and then chalk it up to "stuff happens."
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Old 05-15-2019, 07:56 PM
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It sure sounds like the internet download of the phone upgrade took all the bandwidth - which could destroy anything streaming to the TV. Netflix etc., Cable On Demand or even a regular cable signal if your provider uses IPTV instead of QAM (RF signal).

Without knowing the particulars of your 'cable TV' protocol it is hard to say.
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Old 05-15-2019, 09:12 PM
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I didn't think my phone was THAT good.
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Old 05-15-2019, 10:26 PM
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Originally Posted by kunilou View Post
Wow, can't believe no one can point me in a direction. I'm going to bump this one time, and then chalk it up to "stuff happens."
You’re leaving out a lot of information; if you provided a bit more, you might get more helpful responses.

For example:

- Were you streaming a tv show over the internet? Were you watching something via your cable provider? You mention your TV’s “reception,” which strongly implies that you were watching something over the air (or “OTA”). Which was it?

- If you were watching an OTA broadcast, what channel was it on?

- What router are you using? (I’m asking about the brand and model). Does it allow you to set up a 5 GHz network, or are you restricted to 2.4 GHz?

- What brand of phone are you using? A model would be helpful too.

- Who is your internet provider and how much bandwidth are you paying for?

The question about whether you have a smart tv was likely in the same vein as my streaming/cable/OTA question. To use the ever-helpful car-analogy gambit:

Posting that you “don’t think” you have a smart TV is a bit like answering a mechanic’s question about what kind of car you have with “I don’t think it’s an electric car.” If you can’t provide some basic, concrete information about your problem, then it’s almost impossible to provide a concrete solution.

I’m not just being pedantic (though that is my superpower). If you don’t happen to be savvy about networking, you might not know that you’re not providing enough information to answer your question.

Even without more information, I can tell you that connecting to your router’s 5 GHz network (if it has a 5 GHz radio, but most routers sold in the last year have one) will take care of the interference from your microwave (and likely from your garage door opener as well).

2.4 GHz Wi-Fi uses microwave RF waves to send information—and this overlaps with the frequencies microwave ovens use to cook food. I mean, that’s why they’re called “microwave ovens.”

5 GHz Wi-Fi is less prone to interference, partly because that part of the spectrum isn’t as crowded. But also, radio waves at that frequency are more easily blocked than lower-frequency waves, so 5 GHz networks don’t step on each others’ toes much (unless they’ve physically very close to each other).

Most routers that do 5 GHz will run a simultaneous, parallel network on the 2.4 GHz band, which lets older devices connect even if you prinarily use the 5 GHz band.

Please post some details and see if you’re happier with the responses that come in.

Last edited by EdelweissPirate; 05-15-2019 at 10:28 PM. Reason: Typos
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Old 05-15-2019, 11:35 PM
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Yeah, what TV service, internet provider and phone provider are you using? My first guess upon reading was that the phone overloaded whatever bandwidth your TV was using to stream video. If you're using U-Verse for TV and internet (their TV is basically streaming TV), and AT&T for the phone service, I could see an update delivered from within AT&T's network smooshing all the available bandwidth. It'd be unusual, and it's not necessarily what happened, but it's possible.

So yeah, we need a lot more specifics than what we have to provide anything but wild speculation.
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Old 05-16-2019, 10:08 AM
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My service is Charter, or Spectrum, or whatever they call it this month. I was watching basic cable, with an HDMI cable connecting the TV and cable box. Everything, obviously was digital. The TV is a basic 22" Samsung; it's remote doesn't show anything that suggests it's smart.

The router is a Netgear AC 1750 (or maybe it's ACI 750) "Smart" router model # R6400v2. I'm sure I remember being told it's dual band (and I do understand what that means. As I siad, my wi-fi analyzer app tells me it's on the best possible frequency for either band.

When I say the video "broke up," I mean the audio dropped, the video froze, then pixelated madly. And it all cleared up at exactly the same time as the download stiopped. About 4 seconds.

My phone is a Moto Z2 Play, Android 8.0.0 (up to date.)

Is there anything else that might contribute?

Last edited by Kent Clark; 05-16-2019 at 10:08 AM.
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Old 05-16-2019, 11:44 AM
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It just sounds like the download sucked up all the Internet bandwidth, leaving none for the TV.
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Old 05-16-2019, 11:49 AM
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Originally Posted by beowulff View Post
It just sounds like the download sucked up all the Internet bandwidth, leaving none for the TV.
Concur. It's not that big a mystery: it's the same reason the water pressure drops at the bathroom sink when you flush the toilet: you directed part of the input to your home to a particular high-demand appliance.

Digital cable, even basic cable, is essentially a streaming service. I can assure you from my own experience with Spectrum that if you had been watching something on demand, the chances are about 75% that the whole on demand system would have crashed when you did that update.

Last edited by KneadToKnow; 05-16-2019 at 11:50 AM.
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Old 05-16-2019, 12:15 PM
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this still sounds wonky in that I would expect that the modem/gateway device would have some kind of variation of QoS and set other downstream devices as a lower priority than the tv service to prevent just this phenomenon from occurring every time the wee bairns fire up a minecraft video on their ipad. Challenge is this split usually occurrs before internet appliances meaning the bottleneck is well before the router/modem. I would suspect a weak or faulty splitter in the house or some other wiring problem.

No way in hell is a cell phone crushing the local network on any recent equipment barring other malfunctions.
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Old 05-16-2019, 03:44 PM
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Originally Posted by drachillix View Post
I am a computer tech
I understand networking

this still sounds wonky in that I would expect that the modem/gateway device would have some kind of variation of QoS and set other downstream devices as a lower priority than the tv service to prevent just this phenomenon from occurring every time the wee bairns fire up a minecraft video on their ipad. Challenge is this split usually occurrs before internet appliances meaning the bottleneck is well before the router/modem. I would suspect a weak or faulty splitter in the house or some other wiring problem.

No way in hell is a cell phone crushing the local network on any recent equipment barring other malfunctions.
Thanks, drachiiix. As I said, it was a first for me, but I do have a splitter. I guess I'll make sure everything is still screwed in tightly and see what happens then.
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Old 05-18-2019, 08:45 PM
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Well, that router has QoS settings, but it doesn't seem to know TV from shinola unless you turn it on. So, unless the cable box is before the router, it may have been that the phone got to grab all your bandwidth. If the cable box is after the router (connected by wireless or ethernet), you can set QoS for it's MAC address. Instructions can be found here.
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Old 05-18-2019, 08:47 PM
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Thanks, Kent Clark, for providing those details. I'm reasonably confident that none of the theories put forth so far have to do with the real problem, but I don't pretend to have a strong explanation, either.

Here's what I think we can rule out and why:

I agree with one poster that your phone didn't suck bandwidth from your TV, but for a different reason than the one drachillix mentioned. I also think it's unlikely that there was any sort of RF interference that caused your TV signal to go away, also for technical reasons (see below).

While drachillix' post is on-target for IP networking, it's not applicable to most cable providers--the vast majority of those in the US use quadrature amplitude modulation (QAM) over coaxial cable to customers' modems and set-top boxes. In the context of QAM, your data connection has its own dedicated channels; it doesn't compete with the television portion of your cable signal. They're literally on different channels.

Scabpicker is totally right that AT&T's U-Verse service can see data and TV interfere with each other. U-Verse is IPTV (television over internet protocol) and while quality-of-service controls should prevent data use from killing a TV signal, I totally believe that AT&T misconfigured something and inadvertently choked off the TV's allocated IP bandwidth.

I'm an IP networking guy and a mechanical engineer, but what follows is really the domain of electrical engineers...I welcome any input and corrections from those who know these things better than I do:
  • Each QAM channel is 6 MHz wide and has a theoretical data rate of about 38 megabits per second. That bandwidth can be used for either internet data or regular television channels.
  • One QAM channel can carry up to a dozen standard-def television channels. If you're paying for, say, 150 Mb/s internet speeds, you'll typically have a DOCSIS 3.0 modem, which supports bonding a number of QAM channels together for both upstream and downstream data.

Regarding RF interference, coaxial cable consists of an inner wire, a dielectric insulating layer and an outer conductive shielding layer. (The shielding is covered with another polymer insulating layer as well). That outer conductive layer is called "shielding" because it effectively shields the inner wire from RF interference. I guess it's possible to have a wiring issue that prevents the shielding from doing its job, but that seems really unlikely to me.

Like I said, I don't have an utterly compelling explanation for you, but I can come up with a few plausible ones:
  • "Bad wiring" sounds like a cop-out, but intermittent shorts can cause weird behavior.
  • It's possible that your cable company has some bad hardware upstream from you that was affected by the flood of data you say your phone induced.
  • It was a coincidence. You described the disturbance happening over about four seconds. That's about how long it would take for a cable tech to disconnect the wrong thing, realize that he or she made a mistake, and plug it back in. Or it could have been any of a number of coincidental disturbances. Human beings are wired to perceive causal connections between simultaneous events, and we can't discount the hoary admonition that correlation is not causation.

I hope this helps. Unless this sort of thing starts happening regularly, it may be impossible to find a definitive cause.
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Old 05-18-2019, 09:03 PM
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I just saw that Scabpicker replied while I was composing my post.

To be clear, unless you're using IPTV, your phone (on your router's Wi-Fi network) can't steal bandwidth from your cable TV channels. (And since you're on Charter/Spectrum and you're using coax cables, you're not using IPTV).

The vast majority of US cable providers use "regular" digital cable, not IPTV. And in those cases, your router doesn't know TV from Shinola even with QOS turned on. (QOS stands for Quality of Service, which prioritizes some kinds of data over others).

Your cable signal–encompassing all your TV channels as well as your internet/data connection–is encoded via QAM with 6-MHz channels. One or more of those channels is dedicated (via DOCSIS) to your internet service, while the balance carry cable TV, video-on-demand or other services. Your internet usage can't interfere with your TV signal any more than HBO can interfere with CNN.

The OP's TV weirdness hasn't been fully explained (at least not from where I sit) but almost certainly not a case of his phone "stealing" bandwidth from his TV.
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Old 05-19-2019, 09:27 AM
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Thanks, EdelweissPirate, I'm unfamiliar with non-IP TV these days.
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