U

Visitor

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2 Messages

Thu, May 19, 2022 10:03 PM

Download speed randomly dropping to nothing

I have had 500mb service with Xfinity for 4 years other than couple line services up stream that caused an area outage I have had no network problems at my home using a DOCSIS 3.0 modem Arris SB8200 all those years. I contacted Xfinity to renew my plan and decided to go for 1200mb plan. Shortly after doing that I started having internet download speeds drop all the way down to 0.3mb or 0.0mb download for 3hrs a day usually around 2pm MST to 5pm MST but it wasn't always at the same time of day or same duration. Some days it would drop down for only 20min but do it 3 or 4 times over the course of the evening. I called Xfinity and they said the system does see there is a problem and they dispatched a tech on May 8th I figured while he was here fixing the internet I may as well go grab a DOCSIS 3.1 Modem and get it installed at the same time so can get the full speed I'm paying for. The tech arrived and said he replaced the splitters and filters and re grounded everything and then he replace the modem with the Netgear Nighthawk CM2000. But he also said he found a problem at the tap with a signal being to high (I want to say he said 59db but could be remembering wrong) and that he was going to contact line maintenance department. Shortly after that was notified there would be interruption in my service from May 11-14th. On May 10th the internet was running slow again around 20mb download and I rebooted the Nighthawk Modem but when it powered back up ALL LED began rapidly flashing, I contacted Netgear and they had me preform a factory reset but it did nothing all leds continue to flash rapidly even after hours of waiting and they said i need to ship it to them for service and was most likely caused by my ISP signal. So on May 11th i returned the nighthawk and bought a Motorola MB8611 brought that home and installed in and activated it with xfinity app and it took off and started working with good 800mb download speeds but the Downstream LED is flashing blue instead of being solid and manual says it's Negotiating bonded channels but supposed to go solid eventually. But even with the Motorola I continued getting very slow speeds sporadically but i figured wait until the line repair is complete on the 14th. Well May 14th came and went and I continue to have the same issue with slow to no download speeds. So contacted Xfinity again and they dispatched another tech to come out on the 18th. This tech said he could find nothing wrong at all (of cousre the random issue was not occurring at the time of his visit). He said other than seeing the downstream led on the Modem blinking instead of being solid indicating it's not bonding and suggested I get another modem and then left. I feel 3 different modems is enough to say thats not the issue it is something else. PLEASE HELP attached modem diagnostics, I clear the event log on 18th and so only events from the 19th are in it.

Sorry image bad quality unless download it and view it nothing i do seems to improve the quality of the preview.

Accepted Solution

EG

Expert

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94.3K Messages

1 m ago

Perhaps something intermittent was / is going on. Or perhaps something was fixed behind the scenes. Hope things hold up for you ! Good luck with it !

Contributor

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47 Messages

1 m ago

I'm no expert on what those numbers should be but I know a higher signal to noise ratio is good and errors are bad.  All the SNR values on my NetGear Nighthawk CM2050V are 46.something, power is <=1.3dBmv, and I have no errors reported in the 8 days since I last rebooted it.  Maybe the power is fine (no idea on that one) but you have errors on every channel and your signal to noise ratio looks like what I've seen when I had a problem.  Looks to me like you have a lousy connection and you should keep after Comcast to fix it.

(edited)

EG

Expert

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94.3K Messages

1 m ago

The downstream power levels and the SNR's are good. The uncorrected bit errors are very low.

The upstream power is high (already out of spec on channel number one) and it may be intermittently fluctuating even higher of spec. That can cause random disconnects, spontaneous re-booting of the modem, speed, packet loss, latency problems, and the un-bonding of channels.

In an 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 5-1000 MHz, bi-directional, and no gold colored garbage from Radio Shack, Home Depot, Target, etc. Splitters should be swapped with known to be good / new ones to test.

Also check the coax cable for any damage such as cuts, nicks, kinks, sharp bends, etc.

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 get the techs involved again until it is fixed properly.

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 !

Visitor

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2 Messages

1 m ago

Figured i would update this and i appreciate the responses. Shortly after EG made the post i stopped by Xfinity store and grab one of their modems figuring i would do everything EG said and install their modem so that it wouldn't be pointed at again as the problem. But life happened and I have not been able to get around to doing any of it I have not touched anything. But i have not had a single reoccurrence of the issue since like 12hrs after EG post. The downstream light is now on solid and not a single issue in the last almost 5 days. Crossing my fingers that's the end of it. Attaching new connection info it looks like i dropped from 6 upstream channels to 5 but i'll take it if it's stable.

(edited)

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