T4 Timeout ( Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received ) Explanation: The cable modem did not received a station maintenance opportunity in which to transmit a Ranging Request (RNG-REQ) message within the T4 timeout period (30 to 35 seconds).

When SB8200 reboots did you noticed that your modem power light is also going OFF or stays on?

Yup, my 6141 would format the T4 event in the log and I also looked it up in a DOCSIS pdf.  

I can’t say that I noticed the power light going off on the 8200.  

I assumed that the 8200 was rebooting because the event log on the 6141 would show the reboot following the T4 event.   Since my 8200 doesn’t have an event log, I can’t look in it for a reboot or any event for that matter.

Should I be looking at the lights on the 8200 when the network drops and the modem becomes unresponsive?   By unresponsive I mean that it won’t answer to 192.168.100.1.   I haven’t timed it but I would say that the unresponsive period is like 2-3 minutes.

So I have the R1 connected to an Arris SB8200 cable modem. I have been having issues with T3 and T4 timeouts causing the modem to reboot .A loose power connection is the most common reason a modem may keep restarting. This can be a loose connection at the outlet, or at the power port on the back of your modem. Watch the power lights on the front of the modem as you wriggle both ends of the power connection Note: During startup, all four LEDs will FLASH and then light up SOLID in sequence. If the Power LED does not light up SOLID, please first check the power connection on your SB8200 before contacting ARRIS Technical Support. To resolve connectivity issues, you can try restarting your modem and router by unplugging them, waiting for approximately 30 seconds and then plugging them back in. Restarting them frequently resolves temporary connectivity issues and helps to restore a stable network connection