Have a 2860n that will sit in front of a watchguard.

At present we have a bt 2 wire and 2 IPsec vpn that terminate on the watchguard. The watchguard picks the static ip from the 2 wire via dhcp and we have to port map all services. VPN is very stable

if I swap the 2 wire for the draytek and use either the inbuilt VDSL modem or use the Draytek as a ppoe connection - all works but we have poor stability with the VPN's, traffic drops all the time. We present static IP's to the Watchguard. Any thoughts on what might be causing this on the Draytek.