[timzentu]

What spec of DOCSIS was your old modem? If it was 1.0, 1.1, or 2.0, sorry you lose all support, the older specs had hard bonded channels that HD TV on them after the swap that they informed people of for 2 years before it happened. And they put TV on them since they were degrading channels due to overuse across the entire network (as in across the country).

The later specs allowed for floating channels based on channel maps, which allowed Comcast to bypass those degraded channels.

Note: I'm not an apologist, but I worked for Comcast and for a subcontractor. Comcast treated (at least in my opinion) their customers like wallets that called and complained, but under the subcontractor I saw that since they didn't rewire 100% of all networks purchased, it was common that the older lines were causing the degradation and also reflection on other RF channels sometimes on the other side of an area even. Now if Comcast invested in their network as opposed to buying other companies and calling it investment, this might have been fixed, but that would be decades vs. having every modem that wasn't compliant to the new spec swapped.

[uxp]

The SB6121 is a DOCSIS 3.0 4x4 modem rated for 174mbps, SB6141 is a 8x4 rated for 343mbps, and SB6181 is a 16x4 rated for 686mbps. Outside of their capabilities, the hardware on them are nearly identical. There is nothing "EOL" about the SB6121 except for the idea that it's unable to support 200mbps. It's a perfectly good entry-level modem capable of offering speeds that are over 7 times the minimum definition of "high speed internet".