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Forum Discussion
Mid/High-Split modems affecting TV Cable Pixels Reception?
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...
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?
I split the Comcast/Xfinity Cable initially into two…
Split #1 – Cable Modem, Router, Various Ethernet Connected and Wifi Devices
Split #2 – Split to 4 Devices; 3 TV’s with Xfinity Device and a 3rd Party
Device with Xfinity Cable Card.If the Cable Modem is a Netgear CM2000, I get 950mb download, and 25mb upload, and no TV pixelation. Works great.
If the Cable Modem is an Xfinity XB8 in Bridge Mode not utilizing the built in router, I get 950mb download and 128mb upload. Since increased upload speed is due to recent Xfinity upgrades to take advantage of 32x8 modems. But it causes sporadic TV pixelation on all devices when using TV Cable. My understanding is that since the Xfinity XB8 has 32x8 mid/high-split spectrum, I would get the same results with the Netgear CM3000, which has this newer capability.
From information I am getting, concluding that this is occurring since these newer modems are transmitting on Set-Top Boxes (STB) downstream band, which is causing the pixelation on TV Cable. Noted that it was mentioned a tool called iHat attempts to detect this known problem from Xfinity, but it does not support all STB’s?
So is the incoming ISP cable coax line into the home, have a coax cable line splitter and your making the split with this, one line going to the CM modem and the other line going to the TV STB?
Yes I am making these splits outside of the house. One split line going to the CM Modem, and the other split line going to another splitter which goes to 4 different STB's.