Sorry Dan, we're on completely different tracks...
You should be able to use a digital-to-USB cable which essentially turns your 9700 into either the equivalent of a DVDongle (Terminal Mode) or a high-powered hot-spot (Access Point Mode) without having to deal with the issues of handling G3 routing on you LAN that is hard-wired to UDP port 40000.
It's because of this hard-wiring that I really have no interest in reverse engineering G3 comms, even with the example now in the current XLX software. The digital cable is a much better way to go. It talks raw DStar voice stream packets, much like a DVAP or an MMDVM-compatible modem.
Tom Early