Since the static route needs to point to the LAN side -- no, I have not tried the WAN. And I suspect it is a firmware issue -- and since there is no other response from TP-Link I assume its not...

Model : Hardware Version : Firmware Version : ISP : Firmware Version:0.6.0 0.6 v000e.0 Build 130304 Rel.38108n [B]Hardware Version:TD-W8980 v1 00000000 Problem is really basic: My 8980 is connected...