Has anyone seen this with a Draytek router ?
Mine: 2950, Fw 3.3.0
I was in the process of moving some PCs from real Hardware to virtual environment. During that time, there were no DNS servers present for about 2 hours. The router is setup to use only internal DNS servers.
Suddenly my PPPoE connection dropped about every minute or even stayed down for minutes, Even a reboot of the router did not help.
I could see that the router tried to dial the connection, but, it was not successful.

After typing in the IP adresses of the new DNS servers the connection came up immediately and stayed on since then.

This seems to be some kind of automatic watchdog in the router, more a feature then a bug, but, if you dont know about it, its hard to find.

This behaviour is now confirmed:
if the number of DNS request because of VPN connections to host names exeeds 7 and, if there is no working DNS server, The router will drop the PPPoE connection and is not able any more to establish it until DNS is working again.

Support says, it is questionable that this is a Bug, but I think if this is not a Bug but a feature, it is an undocumented Feature this should be at least written somewhere in the manual, and if this situtation occurs a understandable message must be send via an SNMP trap.