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Problems with CM1150V upstream on Comcast Xfinity
There are a number of past threads (now closed, or I'd be replying to them) about problems people have had with the upstream path on a CM1150V with Comcast Xfinity. I believe I understand the underl...
sleat wrote:So it makes sense that the BGA3131 is designed to operate up to 205MHz. However, notice the sentences I've highlighted. In my case, Comcast is running four upstream QAM channels (no upstream OFDM) at frequencies of 173MHz, 273MHz, 303MHz, and 367MHz. So not only are they asking the CM1150V do do something it was never designed to do, they are blatantly violating the DOCSIS 3.1 spec!
sleat I've read this thread multiple times (having my own Upstream Issues!) and took this at face value;
but only just spotted this fundamental error in your analysis ..........
The Comcast Upstream frequencies are not as you indicate, you are a factor of 10 off
i.e. they are 17.3MHz, 27.3MHz, 30.3MHz and 16.7MHz
i.e. 17300000 Hz (5 zeros) = 17,300,000Hz or 17.3MHz
So actually operating well within the DOCSIS 3.1 Spec and well within the design capability of the Chipset.
As I've said I'm having my own Upstream Issues with my CM1150V (and actually got a replacement from Netgear) and there is definitely a problem - but it's not because it's being asked to operate outside its spec.
We moved to our current home just over 2 years ago. For the first year, our modem was connected to a Comcast drop in our finished basement which has a near-constant temperature of 72F. No issues then. In the Fall of 2022, I moved the modem to my office above the garage. This room has electric baseboard radiators for heat and they are only on for part of the day. In the dead of winter, this room can get down to the low 40s. Almost immediately after moving the modem to the office, we started having problems with the Internet connection going down almost every morning and definitely every weekend. It took me weeks to attribute the issue to the cold temperature. I thought I was crazy thinking that a room temp in the 50s would cause the modem to lose its upstream connection. Seems I'm not crazy after all.
Thanks for the feedback.
I guess for those that have there models in cold place, get them moved to warmer places or maybe have a small cubicle heater that could be placed near the modem to keep it warmer in this colder conditions.
Good Luck.
