Well, having gone to enter the settings again to make a screenshot for you, the router now inexplicably works. I don't believe I've done anything differently so unfortunately I have nothing to give to anyone who finds this thread possibly having the same problem. Thank you for your time anyway.
I do have to tag the WAN traffic yes, but I can't even get any WAN traffic from the router to the internet. If I ssh into the router and try to ping my ISP's default gateway from the router I get no response.
Edit: Just to be clear, if I DHCP the WAN address to my Linux box I get responses from...
Hello.
My ISP requires VLAN-tagging the WAN interface. I've done this through the IPTV tab on the LAN properties page, and it seems to work fine, the router successfully obtains an address via DHCP, but as my title says no traffic actually seems to be routed even though ifconfig shows TX and RX...