In case anyone else has this issue: The issue has been fixed in a non public beta firmware for the Archer C80. Hopefully this will be rolled out in an official releases for all models. EDIT: Link to...

Hello, the DHCP client used in the new software stack your using (i tested it with an Archer C80) can't handle point to point internet connections (If the subnet mask is 255.255.255.255/gateway is...