Hi,<br><br>I have a SB6121 modem which keeps on rebooting after almost every 10 mins. Comcast tech support says the modem is self owned, so they can't access my modem for diagnostics except for sending a signal, which works fine as per them. In the modem logs, I see a lot of "No Ranging Response received - T3 time-out" errors.<br><br>Comcast won't schedule a tech visit saying there is no issue at their end, and that I should contact modem manufacturer Motorola.<br><br>I don't want to buy a new modem unless I am sure there is no issue with the signal, or anything in the modem that can be fixed.<br><br>Please help.
Start here:troubleshooting guide. If you still need help, please post your equipment details (make/model of your modem/gateway/router) and a screenshot of your signal levels and your error/event log. Thank you!