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jboy210's avatar
jboy210
Tutor
Sep 11, 2020
Solved

CM1200 on Xfinity - Stalls, sometimes fast, sometimes slow - Downstream light flashing

Hello,  

 

I have been having problems with inconsistent speeds and multi-minute stalls on my Xfinity Service for about 3 weeks.  In working with Xfinity people they said they were have issues rebooting my CM1000.  So I replaced it with a CM1200.  Now I have the same speed and stall issues and the Downstream light is flashing.   

 

Below are the cable connection and log screens after the logs where cleared this morning.  I appreciate any thoughts on why I am having this problem and how to proceed.

 

I noticed that channel 32 is blank.  Is that normal?

 

BTW, Xfinity rolled a truck on this issue last week.  Tech replaced ends on cables.  Issue still persists. New tech is coming tomorrow, so if anything they should check, let me know!

 

  • Problem seems to have disappeared.  No more downstream light flashing, not stalls, and speeds staying between 930-950 Mbps down and 40-45 Mbps up.  Perhaps Xfinity did something upstream as the tech mentioned to increase capactiy.  Anyway everything seems to be working well.  Thanks for all the help.

8 Replies

    • plemans's avatar
      plemans
      Guru - Experienced User

      Your upstream levels are low. I've found issues when power levels are where yours are at for upstream.

      your downstream levels are high but not crazy high. Just slightly out of optimum spec. 

      Any splitters, amplifiers, or attenuators in line? 

      with 2 modems having the same issue, I'd be looking at the line again. 

      • jboy210's avatar
        jboy210
        Tutor

        Thanks for the info.  The Xfinity tech was here this morning.  He checked the lines again and added a splitter with attenuator which appears to have pulled the downstream power down and upstream power up.   See the attached results and please comment.

         

        After he did that the speed was very slow for awhile (50-200 Mbps on Xfinity's speed test) even at 9AM on Saturday.  But by early afternoon it has climbed up to near expected, 900+ Mbps. However, I still see the downstream light flashing occasionally. 

         

        I will monitor the network to see if this fix is permanenet.  I am especially interested to see what happens Monday.  He did mention with so many kids and workers on Zoom for school and work, they are having to revise (he used the term split) much of their cable plant.