At least , some info about the other side of the vpn tunnel are needed ,but , for make it simple…..just for example… if you want that an host connected to the eth00 (member of the bridge00 , togheter with the vpn00) can surf the web via the vpn tunnel , the default gateway of that host must be “somewhere” after the vpn-server (or even directly the vpn server itself) , on the other end of the vpn tunnel.
greetings