Hi
I have a Watchguard T20W to configure behind a Vigor 2620. Normally when working with BT Business Hubs I would create a DMZ and place the Watchguard in the DMZ by IP address. For all intents and purposes the BT router becomes invisible to the Watchguard for both inbound and outbound traffic. This is not the case with the Vigor 2620. Are there other steps to allow the Vigor 2620 to operate in this way - in effect as a passthrough device?
Thanks in advance.

PPPoE passthrough: https://www.draytek.com/support/knowledge-base/4910

I have enabled pppoe pass thru and set the user credentials in the Watchguard but get no Internet access

Did you set the VLAN tag correctly? Also what does the WatchGuard log show? WG support are super helpful btw, might be worth raising a ticket with them.