Well, we've since since sold our boat and our new one has all new B&G on it, so I may be of limited help going forward. But it turns out I helped the new owner of the boat with something similar.
Long story short, I replaced the wind transducer as he bought the boat, with the new Garmin version that includes a converter cable. I had naively hooked that up to the WIND input on the server but hadn't had any real time to test it before he bought the boat. He called me for help because it was reporting things like 400 MPH wind speeds and the entire server seemed to be acting weird.
We eventually figured out that the WND10 converter does NOT convert from NMEA2k to FDX, but instead to NMEA0183. It didn't come with any documentation
so that was pretty unclear. So you need to hook the WND10 output to a network port. In the case of our old boat the GPS
was hooked to the network port already, but Achilles at Chicago Marine Electronics
pointed out that there's another network port on the autopilot
computer and they're networked together. If that wasn't there he would have needed a multiplexer. We moved the WND10 line to there and it seemed to work
Now, in your case there need to be two lines. I think the network port on the server has two NMEA0183 connections, one in and one out. Both need to be hooked to the WND10. I still have no idea if it converts outbound, but that should at least get the inbound side working.
Hopefully this helps.