How do you expect an RF device to send an IP command? It has to have some native feature to the network to allow this. I mean the mrx-2 is like $400 bucks. Do you really expect to have this sort of functionality or chip set? You can't even walk into a URC networked remote for under ~$1000.

The weak point here is your old remote. While the 980 is a great piece, it's been out almost a decade. Do you have any other decade old equipment you are trying to force to work in a modern way? I don't expect my pronto ts1000 to send network based commands. :-)

Firmware doesn't fix everything. In urc's case, it usually breaks something the first few times.