This past year, I was using the Xfinity XB8 modem which utilized the newer enhanced Xfinity Mid/High-Split spectrum (32x8) allocation in DOCSIS. As advertised saw my upload speed go to over 120 Mbps for Internet access. However, the result was that it caused random pixelation on my TV Cable signal. I then purchased and implemented the Netgear CM2000, and everything is working great, however I am now only obtaining 24 Mbps for upload speed. I am debating whether to try the Netgear CM3000 with the 32x8 capability to see if I can obtain the higher upload speeds without causing pixelation on the Cable TV. Do you know anything about this, as to whether this is an on-going Xfinity issue or a modem issue. Any thoughts if the CM3000 would perform better than the Xfinity XB8 and not create pixelation on my Cable TV signal?

If you want the higher speed tier, the CM3000 supports that. The CM2000 we are unsure about if that will be supported. However if you have cable TV, you should contact the ISP about that since I believe that service runs up to a different TV box which maybe there could be some TV signaling problems with that the ISP should resolved. Cable TV and Internet services are mostly separate coax cable lines. Uness you do some streaming thru the internet services which would come thru the CM2000. We can help you check signaling on the CM2000 modem to see if there could be issues there, however if your not seeing any problems with the internet services, something on the cable TV side maybe effected by the ISPs change in there services. Something to contact them about.

Yes, the CM2000 does not provide the enhanced upload speeds. Would love to contact someone at the ISP to discuss the issue, but for a consumer to be put in touch with a Network Engineer who would understand the issue is difficult at best. Have had some in discussion groups though convey that it is a known problem, but no other information. Thanks for your reply.

Well the ISP should be resolving any Cable TV issues and any Internet signal issues up to the modem side. Something to ask the ISP for escalated support for if your having Cable TV issues. The ISP has been doing lots of changes over past couple of years and could be something there doing maybe causing problems. Something to ask them about on the phone.

CM3000 is just a Cable Modem, I have my own router. Everything works great with the CM2000 Cable Modem and my Router, but only 24Mbps upload. The CM3000 with the 32x8 capability will most likely improve the upload to 128Mbps but gives pixelation on the TV most likely because in mid/high-split mode, the modem transmits in parts of the legacy Set Top Boxes downstream band. Have been told this is a known problem at Comcast according to a 3rd party. Have not heard from anyone at Comcast as of yet.

Is your cable TV set top box connected a host router that's connected to the CM modem or is the set top box connected to the ISP signal using another coax cable line?

Mid/High-Split modems affecting TV Cable Pixels Reception?

13 Replies

FURRYe38
Guru - Experienced User
Apr 21, 2024
If you want the higher speed tier, the CM3000 supports that. The CM2000 we are unsure about if that will be supported.

However if you have cable TV, you should contact the ISP about that since I believe that service runs up to a different TV box which maybe there could be some TV signaling problems with that the ISP should resolved. Cable TV and Internet services are mostly separate coax cable lines. Uness you do some streaming thru the internet services which would come thru the CM2000. We can help you check signaling on the CM2000 modem to see if there could be issues there, however if your not seeing any problems with the internet services, something on the cable TV side maybe effected by the ISPs change in there services. Something to contact them about.
- netmation
  Aspirant
  Apr 21, 2024
  Yes, the CM2000 does not provide the enhanced upload speeds. Would love to contact someone at the ISP to discuss the issue, but for a consumer to be put in touch with a Network Engineer who would understand the issue is difficult at best.
  
  Have had some in discussion groups though convey that it is a known problem, but no other information. Thanks for your reply.
  - FURRYe38
    Guru - Experienced User
    Apr 21, 2024
    Well the ISP should be resolving any Cable TV issues and any Internet signal issues up to the modem side.
    
    Something to ask the ISP for escalated support for if your having Cable TV issues.
    
    The ISP has been doing lots of changes over past couple of years and could be something there doing maybe causing problems. Something to ask them about on the phone.

Forum Discussion

Mid/High-Split modems affecting TV Cable Pixels Reception?