It happened again! But in a way, that's good news because now I know for sure that it happened when the TV was off. I mean, in "idle" not like hardware off with the switch in the back, but still - off.
Anyway, this time I didn't reboot the router, I waited and let it reconnect by itself and checked the logs in the 192.168.1.1 page (how do you call it - admin panel?). Here's the log:
12/3/2014 18:16:40> Call drop because echo reply not received in time
12/3/2014 18:16:40> SNMP TRAP 2: link down
12/3/2014 18:19:15> MPOA Link Down
12/3/2014 18:19:15> SNMP TRAP 2: link down
12/3/2014 18:19:15> SNMP TRAP 2: link down
12/3/2014 18:19:15> SNMP TRAP 2: link down
12/3/2014 18:19:15> SNMP TRAP 2: link down
12/3/2014 18:19:15> SNMP TRAP 2: link down
12/3/2014 18:19:15> netMakeChannDial: err=-3001 rn_p=80544b08
12/3/2014 18:19:16> Last errorlog repeat 2 Times
12/3/2014 18:19:16> netMakeChannDial: err=-3001 rn_p=80544b08
12/3/2014 18:19:18> Last errorlog repeat 8 Times
12/3/2014 18:19:21> netMakeChannDial: err=-3001 rn_p=80544b08
12/3/2014 18:19:22> Last errorlog repeat 9 Times
12/3/2014 18:19:28> netMakeChannDial: err=-3001 rn_p=80544b08
12/3/2014 18:19:29> Last errorlog repeat 2 Times
12/3/2014 18:19:31> netMakeChannDial: err=-3001 rn_p=80544b08
12/3/2014 18:19:32> Last errorlog repeat 1 Times
12/3/2014 18:19:33> netMakeChannDial: err=-3001 rn_p=80544b08
12/3/2014 18:19:51> Last errorlog repeat 20 Times
12/3/2014 18:20:15> netMakeChannDial: err=-3001 rn_p=80544b08
12/3/2014 18:20:17> Last errorlog repeat 1 Times
12/3/2014 18:20:18> netMakeChannDial: err=-3001 rn_p=80544b08
12/3/2014 18:20:29> Last errorlog repeat 3 Times
12/3/2014 18:20:29> MPOA Link Up
12/3/2014 18:20:29> Quick bridge not allow multi-channel
12/3/2014 18:20:29> bridge only stop
12/3/2014 18:20:29> SNMP TRAP 3: link up
12/3/2014 18:20:29> Quick bridge not allow multi-channel
12/3/2014 18:20:29> bridge only stop
12/3/2014 18:20:29> SNMP TRAP 3: link up
12/3/2014 18:20:29> Quick bridge not allow multi-channel
12/3/2014 18:20:29> bridge only stop
12/3/2014 18:20:29> SNMP TRAP 3: link up
12/3/2014 18:20:29> Quick bridge not allow multi-channel
12/3/2014 18:20:29> bridge only stop
12/3/2014 18:20:29> SNMP TRAP 3: link up
12/3/2014 18:20:29> Quick bridge not allow multi-channel
12/3/2014 18:20:29> bridge only stop
12/3/2014 18:20:29> SNMP TRAP 3: link up
12/3/2014 18:20:44> ppp_ready: ch:80563688, iface:804e4fa8
12/3/2014 18:20:44> SNMP TRAP 3: link up
12/3/2014 18:20:44> Accept() fail
12/3/2014 18:20:44> Accept() fail
12/3/2014 18:21:18> dynDNSOrgLogin:Error = -8, retCode
So please let me know if any of the above rings a bell, if any of these errors clarifies a specific reason for the disconnect. I'll appreciate any suggestions, if you want to know any other settings on my router - let me know, I can post anything except the admin password of course ;-)