I am looking for help diagnosing intermittent connectivity issues with my CM1000 modem. I am not sure what clues I should be looking for and I have not been able to detect any patterns to indicate cause. Let me offer some details…
I am an Xfinity customer in my home, and I have been using a Netgear CM1000 modem for around 6 months. Everything worked great for the first 5 months. However, the last month I have been getting hit with maddening intermittent connection problems. I lose all internet connectivity and cannot ping anything on the internet for short periods of time. These issues usually just last a minute or two, but sometimes as long as 5 minutes. Network connectivity eventually comes back without any intervention from me. Some days I have no connectivity issues, other days it happens several times (usually in the most in-opportune times!). I have not noticed any change in the modem lights when this occurs. When I call Xfinity/Comcast support their only suggestion is to reboot the modem. That usually causes the connection to be restored, but I don’t think that is really fixing anything – like I said the connection issues usually only last a minute or two anyways.
The agent I talked to at Comcast said she cannot see anything else on her end. Since I own my own modem, she stated it will likely cost me money to have a tech come out and look at it. Before I break down and have someone come out, I wanted to search for some evidence that is or is not a modem problem. I’m not against buying a new modem either, but am going to be frustrated if I have the same problems.
This behavior occurs on multiple computers - both wireless and wired – which leads me to believe it is a network issue. I swapped out my router for a few days just to see if it was possibly a router issue. The same issues occurred with the replacement router, so I think I can rule that out as well.
I did chat with my good friend Google a bit and learned to check the power levels. The power levels seem ok as they fall between the -7 to 7 range for downstream and 38-48 for upstream.
I haven’t touched any cables lately, but did double check the cables I had access to to make sure they were connected tightly.
My Hardware version is 2.02 and firmware version is V3.01.04. I understand that Xfinifity/Comcast controls pushing out the firmware updates so there is not much I can really do about adjusting firmware.
I do have an older (slower) modem I suppose I could go back to for a while and see if I have problems with that.
Any thoughts/ideas would be appreciated.
