Review on 🔌 ARRIS SB6121 SURFboard 4x4 DOCSIS 3.0 Cable Modem -Retail Packaging- Black by Charlie Dillon

Although the modem is advertised as Comcast compatible, the reality is more complicated. Yes, the modem works. However, throughput is down to about 10 Mbps and up to 5 Mbps. I've called Comcast three times to complain that I'm not getting the 25 Mbps I paid for. They sent technicians three times. A third tech told me he had seen similar issues with other surfboard modems. Eventually he ran diagnostics and found that the Comcast system didn't know the modem was connected, even though the connection was working. He called his supervisor to report the anomaly. (He has also seen this problem with surfboard modems.) The supervisor seems to have had this problem as well. In short, this modem works with Comcast, but not very well. Some technicians are aware of this. But it seems that the experience of the technicians has not reached the headquarters. Comcast really needs to remove surfboards from its list of compatible modems. Or at least educate customers about the limitations of modems. The tech advised me to use a Comcast gateway modem to ensure I get the bandwidth I paid for. It's expensive compared to surfboards, but you can find used equipment for less.