NOTE:

Vigor 2700 is not designed for this kind of scenario and this is not a permanent solution, the default route will be flushed when you reboot your V2700VG. There is no setting can make this permanent.

1.)    Add default route to the Draytek router.

ip route add 0.0.0.0 0.0.0.0 192.168.1.x 0 default
(change 192.168.1.x to your 3G IP) this command will change the V2700’s default route to 3G modem’s IP.

2.)    Setup DNS server addresses on LAN settings page of the DrayTek router.

 

Another scenario is like this:

Virgin Media Cable internet -> Cisco Cable modem (192.168.100.X) -> Netgear wifi router (192.168.1.X) -> Draytek 2700VG ata (192.168.1.254)

1.)    Add default route to the Draytek router.

ip route add 0.0.0.0 0.0.0.0 192.168.1.x 0 default (change 192.168.1.x to your Netgear’s LAN IP) this command will change the V2700’s default route to Netgear’s LAN IP.

2.)    Setup DNS server addresses on LAN settings page of the DrayTek router.