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Modem Loses Connection Randomly - US/DS Flashes

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Modem Loses Connection Randomly - US/DS Flashes

Hello,

 

We've been having an issue for the past few months with modem going offline, it's been very random, and initially we thought it was our router. But as the problem got worse, we noticed the modem would lose complete connection to Comcast. US/DS light flashes, never goes online, until maybe hours later. Sometimes it comes back for a few minutes and goes back out. Then it won't happen for a few weeks and the cycle repeats. I've already called Comcast a few times and have a tech scheduled to visit this coming Friday, but looking for any further feedback/suggestions, before they come. As I would hate to be charged if it's something within my house. This past Sunday, we swapped the modem with a newer one (ours was old) and it still does it, same exact behavior. 

 

Setup: 

Cable drop from attic > Coax/HDMI Wall Plate > Splitter (2way Comcast supplied) Modem TG1682G and Comast DVR 

 

Replaced: 

Cable between wall plate, splitter (comcast supplied), coax cable for modem and TV

 

We never have issue with the DVR that is on the same line as modem. I'm thinking of trying to replace the wallplate with a new one, or just bypass wallplate and use an HDMI coupler and connect the drop from the attic, directly to splitter. If I buy my own splitter, what specs should I be looking for? 

 

Last year we tried X1 and it just would not work in two rooms (X1 worked fine where the modem currently is). So their last tech redid a bunch of the end connections and changed the splitter in the attic and outside box. To be honest, I wasn't too keen on this tech and was afraid he opened a can of worms. Not sure if this is somehow related, but thought it is worth mentioning. 

 

Here's one thing I found interesting last night. The modem was offline for 2 hours, I started to fiddle around with it, did multiple hard reboots. I decided to bypass the splitter and as soon as I connected directly to wall plate and rebooted, modem went online. So I figured if I plugged it back in line with the splitter, modem should technically not connect. Well, it connected, with the splitter in line. But then 3 hours later, went offline. I left it like that all night. I wokeup this morning and decided to try a hard reboot first. Still blinking US/DS and doesn't go online. Before I left for work, I decided to just try unplugging the coax cable and then plugging it back in and reboot the modem. Modem went online! And it's been online for past 4 hours. I did some searching on google and found a couple people report the same behavior, modem goes offline and doesn't come back online, until the coax cable is reseated. Sadly, they never followed up what their solution is. But sounds like maybe there could be a bad ground somewhere? 

 

Any input would be appreciated. Our house is only 5 years old, we bought it as new construction. We thought about moving the modem to another outlet, but due to wifi issues, where it's at right now, is the best spot for wifi to work. And since the problem is so random, we wouldn't know if it's really fixed. 

Expert

Re: Modem Loses Connection Randomly - US/DS Flashes

Sounds like the signals from the pole are too weak. When you do have a connection, what do the modem's signal stats look like ? Try getting them here; http://192.168.100.1 or here http://10.0.0.1

Please post the *Downstream Power Level*, the *Upstream Power Level*, and the *SNR* (Signal to Noise Ratio) numbers.




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Frequent Visitor

Re: Modem Loses Connection Randomly - US/DS Flashes

Thanks, I will check this tonight and post the data. 

Frequent Visitor

Re: Modem Loses Connection Randomly - US/DS Flashes

Here's the information, attached screenshot. 

Screen Shot 2017-04-11 at 5.39.12 PM.png
Expert

Re: Modem Loses Connection Randomly - US/DS Flashes

Yep. The signal stats are marginal to out of spec and may be intermittently fluctuating even farther out of spec. That can cause random disconnects, spontaneous re-booting of the modem, and speed and latency problems.

Stuff that you can try which may or may not apply;

 

In a self troubleshooting effort to try to obtain better connectivity / more wiggle room, check to see if there are there any excess/unneeded coax cable splitters in the line leading to the modem that can be eliminated/re-configured. Any splitters that remain should be high quality and cable rated for 5-1002 MHz, bi-directional, and no gold colored garbage from big box stores like Home Depot, Lowes, Target, Wal-Mart etc. Splitters should be swapped with known to be good / new ones to test

If there aren't any unneeded splitters that can be eliminated and if your coax wiring setup can't be reconfigured so that there is a single two way splitter connected directly off of the drop from the street/pole with one port feeding the modem and the other port feeding the rest of the house/equipment with additional splits as needed, and you've checked all the wiring and fittings for integrity and tightness and refresh them by taking them apart then check for and clean off any corrosion / oxidation on the center wire and put them back together again, then perhaps it's best to book a tech visit to investigate and correct.

 

Your drop line may need to be replaced or the problem could lie in the neighborhood lines somewhere.




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Re: Modem Loses Connection Randomly - US/DS Flashes

So I got a quality splitter and installed it last night, the signal levels are the same. This morning, the upstream was pretty much out of spec and sure enough the modem went offline 2 hours later, but then came back online after 30minutes. 

 

Just now received a call from Comcast Advance Support and they claim to have reviewed my signal levels and determined it was "within spec" and they should cancel the appointment for a tech on Friday. I kindly advised them I checked the signal levels last night and today and they're borderline out of spec and that the issue is very random. The person on the phone was under the impression the internet didn't work at all. So I'm glad I answered the phone and got them to keep the tech visit for Friday. 

 

Tonight, I'm going to try plugging in the modem into another outlet and check the signal levels. 

Expert

Re: Modem Loses Connection Randomly - US/DS Flashes

Good luck !



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Re: Modem Loses Connection Randomly - US/DS Flashes

Thanks! 

 

I moved the modem to the lower level of the house and getting same levels. 

 

It's safe to say at this point, when the modem goes offline, only thing that fixes it right away is to disconnect the coaxial cable and plug it back in, reconnects within seconds - without having to reboot modem. 

Expert

Re: Modem Loses Connection Randomly - US/DS Flashes

FWIW, that's not a "Fix". Get a tech visit to investigate as stated. Good luck !



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Re: Modem Loses Connection Randomly - US/DS Flashes

Tech visit went very well this evening. Tech was very polite and knowledgable. He determined the signal coming into the house was good, but inside the house the signals were all out of spec. He installed an AMP and we had to use our spare bedrooms cable outlet, since there was no power outlet in the attic where the main line comes in. 

 

I decided to ask him if this is why X1 wouldn't work last time we tried it, he said yes. The last tech that came out to troubleshoot it, should of figured out there was an issue inside the house and provided a solution. We could of avoided having internet issues and still have X1. So we'll probably be giving X1 another shot. 

 

Attached screenshot of our signals now. They look much better, as far as I can tell. 

 

Thanks for the help! 

Screen Shot 2017-04-14 at 9.29.05 PM.png
Expert

Re: Modem Loses Connection Randomly - US/DS Flashes

Yep. Glad that it got sorted out !


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Re: Modem Loses Connection Randomly - US/DS Flashes

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