Internet drops frequently, MG7550 modem self reboots almost daily since early March 2023

CMTS check is a good idea, and you're on the right path.  Looks like you're getting beat up on the downstream power.  Upstream isn't pushing very hard, so that's good. 

What's cheap and fast if you want to roll the dice and fix it yourself?  A 6dB forward path attenuator.  Less than $10 on Amazon.  They did some work in my neighborhood after a drunken neighbor ran over the cable box in the yard, and the downstream power doubled instantly from what it was.  It was causing havoc.  I've tried to post the link on Amazon in the past, but the bot eats it.  It is easy enough to search for, so I'll save the mods some work.

Try to knock that signal down a bit and see if it magically fixes it.  It's not going to make it any worse and may save time and misery. 

@user_bcaab9 

Question. So the problem was happening before you removed the 3-way splitter ?

@flatlander3​ , @EG, , no luck - my internet keeps dropping 1 or 2 times daily, even after installing the 6dB Forward Path Attenuator to reduce the Downstream Pwr levels..

same issue, connection suddenly drops, then MG7550 self-reboots, and Modem event logs shows T3-timeout.

Overnight and this morning the Modem Connection tab noticed a high number of "Corrected" errors per screenshot attached, higher than i had seen earlier.

Is there any way to get Comcast/Xfinity technicians involved?

Any advise greatly appreciated! thank you!

                                          (screenshot taken Friday 3/24/23 8:56amCT)

Signal is in a better range, but Yikes!  Now you got a frequency dependent reflection!  Big swing on power is new.  I still don't know how you're getting away with soft correctable errors and not

Got a better cable for the modem?  Something like this?  https://www.amazon.com/dp/B09TNM77TZ/ref=twister_B09ZNS9D71?_encoding=UTF8&psc=1

(Same Tyco connectors they use) 

3-4 dB of cable tilt should not problematic. And if the problem was too much downstream power, the original 3-way splitter dropped the power down even more than the current attenuator does. You stated that the problem existed even before you removed that splitter. Perhaps the problem was actually with the upstream power ? The original splitter in the line would have raised it to the out-of-spec value of around 52 to 53 dB...

P.S. FWIW, it is not necessary to use Flooded / "Direct Burial" type of coax for indoor usage. And I'm not sure if that 70 Ohm rating is a typo. 75 Ohm coax cable is the norm.

@flatlander3 , @EG Thank you both for your suggestion, much appreciated. You gave me an idea to isolate and test the cable run.

 My modem is sitting upstairs on 2nd story room, and I estimated about 50ft coax run from the basement thru rafters and up the walls to 2nd story.

I will bring the modem down into the basement and plug it into a short 15 foot Coax cable (where the 3-way splitter was) that connects directly thru the wall to the outside Comcast box.

If that connection in basement improves the frequency reflection and the errors, then that would (hopefully) point to the 50ft coax cable running upstairs.

Will give it a shot over the weekend and let you know. Thanks!!

@flatlander3 , @EG, quick update

• Moved modem downstairs to basement, now is just 15ft of coax from modem to outside wall
• still experiencing 1 or 2 daily internet drops ;-(
• excessive "Corrected" numbers , 0 "Uncorrected"
• Downstream pwr 8.5-12.3 dBmV, with 6dB Fwd path attenuator installed
• Comcast had service outage on Sunday 3/26 for 2 hours

It seems eliminating the 50ft coax run from basement to 2nd story made no difference.

Suspect either issue outside home, e..g: bad COAX cable from home to CMTS, or some issue at CMTS?

Any thoughts? Thank you!

screenshot

Tue 3/28/23 - downstairs in basement, with 6dB Attenuator

Regards,

That is really quite amazing you can get that many correctable errors, and yet not a single uncorrectable?  Sure.  Hardware is fixing those, but still.  Looks weird to me. I'd expect that to stumble from time to time. 

You might be stuck scheduling a tech visit to take your house out of the equation, and check the line to see what is coming in from the street, unless @EG  has a better idea.

@user_bcaab9 

Well this may or may not be the root cause of the problem (YMMV) but the downstream power is still too high. If you wanted to, you could try using another -6 dB FPA piggybacked with the existing one and see.

An F.Y.I. There are other signal stat values that can't be read by the modem. They are the "Upstream Rx Power" (Upstream Receive Power Level), the "Upstream SNR Ch." (Upstream Signal To Noise Ratio), and the "Upstream ICFR" (In Channel Frequency Response). These are as equally important in diagnosing connectivity issues as are the modem's stats.

I'm going to escalate your issue to the Comcast corporate employees (The Digital Care Team) who are available to these boards. They will be able to poll the CMTS (Cable Modem Termination System) to check for any real-time degradation and / or error reports, see your node / cable plant, and modem health, and see whether or not everything is in the green zone. They can also see a history plot for the modem and poll the CMTS for those upstream receive signal stats.

You should get a reply here in your topic. They may suggest that you get a tech out to investigate the problem.

Bear in mind that if the premises facing techs can not find or fix a problem at your home, it is they who are responsible for escalating it to their line / network / maintenance dept. techs. The problem may lie beyond your home in the local neighborhood infrastructure somewhere but it is their S.O.P. to start at the home. And if the problem is found to be on their side of the demarcation point, there will not be any charge.

Good luck !

@flatlander3 @EG Big THANK YOU to both of you, really appreciate all your patience and support!!! ;-)

Regards

@user_bcaab9 

Please post back here with how things turn out.

@flatlander3 @EG 

just a quick update:

• Continue to experience 1-2 drops daily
• Modem Software Version now shows 7550-5.7.1.43 (versus .4 a few weeks back) so seems Comcast updated it
• Noticed a pattern when connection drops it switches channels 621mhz or 447mhz, when Acquire Downtream Channel is 621Mhz it has thousands of Corrected errors overnight , vs 447Mhz only a few dozen corrected errors . Either way i get dropped

I’ve not heard from Comcast

just curious, do we know if Comcast Digital Care Team had a chance to poll CMTS for statistics and errors? please advice 

thank you!

Have you tried using an additional attenuator ? If so, and it didn't help, I can re-escalate this. Looks like it may have slipped through the cracks..

Will do. Looks like there is something intermittent going on possibly with the local plant / infrastructure as was stated. Good luck with this !