We have 3 sites, with our two remote sites connection to head office via LAN-to-LAN VPN's. All 3 sites use DrayTek 2900's with firware version v3.3.1.1_RC2 (this is a release candidate that DrayTek suggested I try, but sadly it made no difference). The only way to re-establish the VPN's once they have been dropped is to restart the router.

Head office is set to dial out to both sites, with both the 'Always on' and 'Enable PING to keep alive' (pinging a server in the remote offices) options ticked. However, at random intervals the VPN's drop, logging IKE_RELEASE VPN : Dial-out Profile Index = 7, Name = Shepton (for one connection, and '6' & 'Wincanton' for the other connection).

I first tried swapping the router with one at another site, and then had all three replaced, but that failed to solve the problem.

Is anyone aware of anything that could cause the VPN's to drop randomly like this? Thanks.