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Greatly inhibited download speeds due to RCS Partial Service and Lost MDD Timeout

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Greatly inhibited download speeds due to RCS Partial Service and Lost MDD Timeout

Hello!

Issue Description

I've been having intermittent internet speed issues since moving to a new apartment complex. We pay for the 400mbps plan(Performance Plus with the Extreme Pro Internet addon), however our download speeds are closer to 10-30mbps on average. We noticed that rebooting the modem brings the speed back up to ~100-400mbps for a period of about 5 minutes, but then it quickly degrades in quality back down to the original 10-30mbps.


Hardware

Modem: Arris SB6190
Router: Netgear Nighthawk xr500


What has been tried so far

  1. We bypassed the router, plugging-in via hardwired connection to the Modem directly. Same problem persists. Fast speed tests immediatelay after reboot, degrading in speed over a few minutes after that.
  2. Ensured Netgear router was configured with QoS settings disabled
  3. Used TP-LINK Archer C7 router to test as well, same results
  4. Restarted router(s) independent of modem, same results
  5. Used five different Ethernet cables
  6. Found a forum post (specifically the section explaining what "RCS Partial Service" means) that explained why my Modem's Event Logs were referencing and decided to bring it to this support forum.

Has a tech visited?

We had a professional tech assist with initial installation and setup, but not for this issue directly as of the time of my writing.


Modem Error Logs

Time Priority Description
Wed May 15 20:11:36 2019 5 Lost MDD Timeout;CM-MAC=b0:da:f9:ed:ff:5f;CMTS-MAC=00:01:5c:6b:7e:4d;CM-QOS=1.1;CM-VER=3.0;
Wed May 15 20:11:42 2019 5 RCS Partial Service;CM-MAC=b0:da:f9:ed:ff:5f;CMTS-MAC=00:01:5c:6b:7e:4d;CM-QOS=1.1;CM-VER=3.0;
Wed May 15 20:11:51 2019 5 Lost MDD Timeout;CM-MAC=b0:da:f9:ed:ff:5f;CMTS-MAC=00:01:5c:6b:7e:4d;CM-QOS=1.1;CM-VER=3.0;
Wed May 15 20:11:52 2019 5 RCS Partial Service;CM-MAC=b0:da:f9:ed:ff:5f;CMTS-MAC=00:01:5c:6b:7e:4d;CM-QOS=1.1;CM-VER=3.0;
Wed May 15 20:12:31 2019 5 Lost MDD Timeout;CM-MAC=b0:da:f9:ed:ff:5f;CMTS-MAC=00:01:5c:6b:7e:4d;CM-QOS=1.1;CM-VER=3.0;
Wed May 15 20:12:40 2019 5 RCS Partial Service;CM-MAC=b0:da:f9:ed:ff:5f;CMTS-MAC=00:01:5c:6b:7e:4d;CM-QOS=1.1;CM-VER=3.0;
Wed May 15 20:12:40 2019 5 Lost MDD Timeout;CM-MAC=b0:da:f9:ed:ff:5f;CMTS-MAC=00:01:5c:6b:7e:4d;CM-QOS=1.1;CM-VER=3.0;
Wed May 15 20:12:47 2019 5 RCS Partial Service;CM-MAC=b0:da:f9:ed:ff:5f;CMTS-MAC=00:01:5c:6b:7e:4d;CM-QOS=1.1;CM-VER=3.0;
Wed May 15 20:12:59 2019 5 Lost MDD Timeout;CM-MAC=b0:da:f9:ed:ff:5f;CMTS-MAC=00:01:5c:6b:7e:4d;CM-QOS=1.1;CM-VER=3.0;
Wed May 15 20:12:59 2019 5 RCS Partial Service;CM-MAC=b0:da:f9:ed:ff:5f;CMTS-MAC=00:01:5c:6b:7e:4d;CM-QOS=1.1;CM-VER=3.0;
Wed May 15 20:13:25 2019 5 Lost MDD Timeout;CM-MAC=b0:da:f9:ed:ff:5f;CMTS-MAC=00:01:5c:6b:7e:4d;CM-QOS=1.1;CM-VER=3.0;
Wed May 15 20:13:46 2019 5 RCS Partial Service;CM-MAC=b0:da:f9:ed:ff:5f;CMTS-MAC=00:01:5c:6b:7e:4d;CM-QOS=1.1;CM-VER=3.0;
Wed May 15 20:14:05 2019 5 Lost MDD Timeout;CM-MAC=b0:da:f9:ed:ff:5f;CMTS-MAC=00:01:5c:6b:7e:4d;CM-QOS=1.1;CM-VER=3.0;
Wed May 15 20:14:09 2019 5 RCS Partial Service;CM-MAC=b0:da:f9:ed:ff:5f;CMTS-MAC=00:01:5c:6b:7e:4d;CM-QOS=1.1;CM-VER=3.0;
Wed May 15 20:14:24 2019 5 Lost MDD Timeout;CM-MAC=b0:da:f9:ed:ff:5f;CMTS-MAC=00:01:5c:6b:7e:4d;CM-QOS=1.1;CM-VER=3.0;
Wed May 15 20:14:25 2019 5 RCS Partial Service;CM-MAC=b0:da:f9:ed:ff:5f;CMTS-MAC=00:01:5c:6b:7e:4d;CM-QOS=1.1;CM-VER=3.0;
Wed May 15 20:14:58 2019 5 Lost MDD Timeout;CM-MAC=b0:da:f9:ed:ff:5f;CMTS-MAC=00:01:5c:6b:7e:4d;CM-QOS=1.1;CM-VER=3.0;
Wed May 15 20:15:17 2019 5 RCS Partial Service;CM-MAC=b0:da:f9:ed:ff:5f;CMTS-MAC=00:01:5c:6b:7e:4d;CM-QOS=1.1;CM-VER=3.0;
Wed May 15 20:15:22 2019 5 Lost MDD Timeout;CM-MAC=b0:da:f9:ed:ff:5f;CMTS-MAC=00:01:5c:6b:7e:4d;CM-QOS=1.1;CM-VER=3.0;
Wed May 15 20:15:25 2019 5 RCS Partial Service;CM-MAC=b0:da:f9:ed:ff:5f;CMTS-MAC=00:01:5c:6b:7e:4d;CM-QOS=1.1;CM-VER=3.0;

A note on the logs, these fill up frequently, with new errors happening at a rate of about 3-8 per minute. Another article i was reading mentioned that prolonged Partial Service and MDD timeouts can also lead to the router falling over and going offline, which has also happened to me a few times (the router going offline and rebooting due to no action on my end).


Screenshot of Modem Bonding Channels and Powers

https://i.imgur.com/NiMF162.png


At this point I'm beginning to believe this might be an issue with my apartment complex's wiring, configuration, or another problem upstream since the frequency of "RCS Partial Service" and "Lost MDD Timeout" events in my logs are only appearing when the speed decreases in the minutes following a modem reboot. These appear to be some sort of issue outside of my immediate control (such as just purchasing a new modem [the router is 3 days old and was an attempt at fixing it before digging deeper]), I figured it was time to reach out to the support forums for some insight on what my next steps should be.

Official Employee

Re: Greatly inhibited download speeds due to RCS Partial Service and Lost MDD Timeout

Hi dylanb! I want to help you out. 

Can you please private message me your full name? Thank you for posting to our forums. 

To send a private message, please click my name "ComcastMartin" then select "Send a Message" on the right side.
 


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New Poster

Re: Greatly inhibited download speeds due to RCS Partial Service and Lost MDD Timeout

A new modem has arrived and the issues are mostly resolved. Our speed went from 20/10 to around 120/15, however we do pay for 400/10.  

Silver Problem Solver

Re: Greatly inhibited download speeds due to RCS Partial Service and Lost MDD Timeout


@dylanb wrote:

A new modem has arrived and the issues are mostly resolved. Our speed went from 20/10 to around 120/15, however we do pay for 400/10.  


What does the beta speed test say?

https://speedtest-beta.xfinity.com/

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I am just a customer, volunteering my time to help other customers here in the Forums.
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Expert

Re: Greatly inhibited download speeds due to RCS Partial Service and Lost MDD Timeout

You have some signal problems in the downstream. Some of the SNR's are too low / out of spec , and some channels are not locking which indicates that there is a noise ingress in to the line problem somewhere..



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I am a Customer Expert volunteering my time to help other customers here in the Forums.
We ask that you post publicly so people with similar questions may benefit from the conversation.
Was your question answered? Mark the post as Best Answer!