Hi,

We have a client with a 2710n, firmware 3.3.6.1
They run 2 SIP handsets on the LAN connected to a remote PBX
After a while, one of the handset's looses it connection, you cant register the phone even after rebooting
If you restart the router, everything works fine again..... then the connection is lost a few days later

The router just runs nat, with no firewall settings or CSM other than the default factory settings
sip_alg is disabled.

It always seems to work fine for one SIP handset, but not when you try to run 2 - I suspect the nat port is being blocked after a while and stops that handset from ever opening up a new port.

Does anyone have any ideas what this could be ???

Try turning the Data Filter off as a temporary work-around, it's a bug and you need to get hold of a beta firmware from Draytek to fix it totally. Apparently it'll be fixed when 3.3.7 is released though.

Thats not going to help as we'll then have netbios packets flying around!
The default data filter stops netbios packets going out on the wan.