We have moved a decommissioned network which had a working vpn on an old Sonicwall TZ190 which was behind an sdsl vigor 3300 router.
The vpn setup was an IKE auth with a shared secret key and the clients connected to the vpn using the GVC from Sonicwall to the public ip of the draytek router.
The draytek router was set to open and forward all ports to the Sonicwall.
We moved the network and had to change from SDSL to ADSL due to poor connection stats from the ISP.
The replacement router is a Draytek again 2850 VDSL/ADSL in ADSL mode, the ADSL is up and port forwards are set to the Sonicwall. But the vpn will no longer connect.
The client log reports failure to negotiate ISAKMP phase 1 and also the error "failed to find mac address in system interface table"
The public Ip is right and the only change has been the router, so is this something to do with vpn passthrough or am I missing something. Nat traversal is ticked on at the Sonicwall and interestingly there are no packets logged on the Sonicwall for IKE auth, or VPN connection attempts.
Desperate for help, max points to be awarded for bang on answer