redkomrad's profile

New Poster

 • 

7 Messages

Friday, April 3rd, 2026 6:22 PM

Large Number of Uncorrectables on download channels

Symptoms: 

Large Number of Uncorrectables on download channels.
Download mode switches from Docsis 3.1 to 3.0 intermittently
Upload mode is always Docsis 3.0

CM: Arris SB8200

Standard Specification Compliant Docsis 3.1
Hardware Version: 6
Software Version AB01.02.053.05_051921_193.0A.NSH
Cable Modem MAC Address : redacted
Serial Number: redacted


Could a tech look into this? 

Oldest First
Selected Oldest First

Expert

 • 

117.7K Messages

28 days ago


The upstream power is too high / out of spec. The downstream power is a bit on the low / weak side as well. 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 any excess/unneeded coax cable splitters in the line leading to the modem that can be eliminated/reconfigured. Any splitters that remain should be high quality and cable rated for 5-1002 MHz, bi-directional, and no gold colored garbage from Home Depot, Target, Wal-Mart, 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, abrasions, kinks, sharp bends, or animal chews.

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.


Good luck with it !

New Poster

 • 

7 Messages

Thanks. In the cable box outside of my home, I had 5 way splitter connected from when I used to use MocA to supply ethernet to various rooms. I don't use that any longer, so I disconnected it with the goal of connecting the  incoming male coax to the male coax of the room my CM is in , but I didn't have a female to female barrel connector on hand. I used a 2 way splitter to connect them for now. 

For downstream, Channels 7 and 27 stand out for uncorrectables. 7, 27, and 193 stand out for correctables. I'm guessing that my upstream power is still on the high side.  I do see a lot more "unlocked" channels when I refresh the CM status page, so I hope the parts I ordered help with that.

I ordered  a female to female barrel connector for Comcast coax to house coax connection, a new coax cable for wall to CM connection, and a new Hitron Coda56 modem to see if that helps.  

I checked the cable ends and didn't see any corrosion or dirt. No apparent damage to exposed cables outside or inside the home.

I'll post another update after I install the new parts and retest. Thanks for the tips! 

New Poster

 • 

7 Messages

@redkomrad​ I captured a screenshot showing unlocked channels , for additional info.

New Poster

 • 

7 Messages

Inside, I replaced the cable from the wall plate to the cable modem and installed the Hitron Coda56 modem.  

Outside, I connected the Comcast coax to house coax with a female to female coupler / barrel connector. 

The contacts are all clean and no corrosion. 

Here is the stats page from the new modem after 5 hours 43 minutes of uptime.

I read in other forums that correctable errors are ok, but there should not be any uncorrectables. Is that correct?

I noticed channel 193 is gone , and channel 7 is the worst offender for uncorrectables. 

What should we do next? 

Official Employee

 • 

2.2K Messages

 

redkomrad Can you please send us a DM. You can start by clicking the chat icon located in the top right corner of your forums' page when signed in. Once there, you can direct your messages to "Xfinity Support." Please add your full name and service address to help us locate your account. Let me know if you have any questions. 

 

I am an Official Xfinity Employee.
Official Employees are from multiple teams within Xfinity: CARE, Product, Leadership.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Please, mark a reply as the Accepted Answer.tick

New Poster

 • 

7 Messages

Done! We'll see what happens next.

Expert

 • 

117.7K Messages

26 days ago

If there is nothing more that can be done to improve the connection quality, then you'll need a tech visit as stated. 


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 up 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 !

Expert

 • 

117.7K Messages

25 days ago

@redkomrad @XfinityBrianH 

Please circle back here and post any possible solutions for the issue here in these open public forums so that all readers here may benefit from the exchange / info. This is in keeping with the spirit for which these public help forums were originally intended. Thank you.

forum icon

New to the Community?

Start Here