Got a Vodafone supplied Huawei HG556a trying to get Wake on Lan working through it.

Have forwarded port 5850 on the router to the correct PC, using a WOL app on my android phone i can get it to start the PC from the LAN but not remotely (using 2degrees 3g rather than home wifi).

Obviously the router is blocking the broadcast IP address used when sending the magic packet from a WAN.
Can't see how to port forward for the broadcast IP (router wont allow it). How do i configure this?