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New CM205V Interferes with TV Signal
When a CM2050V is connected to a three-way coax splitter (the modem, and two TVs to Xfinity Voice/Data/Cable television service, it disrupts the signal to the two tvs. Disconnect it, and the TVs are fine. Disconnect the standalone router, problem still exists. I rolled back to a Netgear C7100V in passthrough mode, and everything works again. The problem is definitely the modem. The only reason I bought this modem is because I received an email advising that Netgear will stop support for the C7100V on 7/31/25. Neither Comcast nor Netgear support can explain what's going on, much less make it work. Would be better to upgrade to CM2050V, but the C7100V will stay in place for now ANY ideas how to solve this problem? Thanks in advance.
Way too many correctable/uncorrectable errors for a 24 hour period of time.
DOCSIS 3.1 is backward compatible with DOCSIS 3.0. I do not think DOCSIS 3.1 is backward compatible with DOCSIS 2.0. If you are looking at DOCSIS 2.0 hardware, you want to check the coax type to ensure it is correct for the current DOCSIS 3.1 connections (RG6).
What were the upload/download throughputs with your new splitters in place?
You might find some ideas in chapter 3 of this reference: https://www.duckware.com/tech/solving-intermittent-cable-modem-issues.html
42 Replies
One of the other big tells is the ofdma channels. Your normal ones are pretty much in range (ish). The ofdma has 1 channel barely in range and the other outside of it. Something is restricting its power levels. (which is why the docsis 3.0 device works fine but not the docsis 3.1 device) So its either the splitters or something in the line causing issues on those channels range.
New splitters cleaned things up but still had problems with occasional pixilation and anomalies in ever-changing areas of the screen. Rolled back to the old modem, things back to normal again. Report attached. Somehow this modem is not compatible with my system. Maybe it's the DOCSIS 2.0 cable boxes I use. Maybe it's something else. Couldn't get the new cable box to respond to the IR emitter connected to a legacy universal remote system, so that's not an option at present. Internet speeds are the same on the new and old modem. Thanks to all for your time and effort.
For both, power levels are good now for both, however both modems are seeing too many Correctables and Un-correctables.
The C series is DOCSIS 3.0 and the CM is 3.1.
Something maybe happening down the line after the modem.
Way too many correctable/uncorrectable errors for a 24 hour period of time.
DOCSIS 3.1 is backward compatible with DOCSIS 3.0. I do not think DOCSIS 3.1 is backward compatible with DOCSIS 2.0. If you are looking at DOCSIS 2.0 hardware, you want to check the coax type to ensure it is correct for the current DOCSIS 3.1 connections (RG6).
What were the upload/download throughputs with your new splitters in place?
You might find some ideas in chapter 3 of this reference: https://www.duckware.com/tech/solving-intermittent-cable-modem-issues.html
Speedtest gives me 700+ Mbps upload and 40+ Mbps downloads, pretty much the same as before. Thanks for the article. Could this be them (Xfinity) and not me?
Yes.
