OK, so that's Npcap, not WinPcap - the original remote-capture client code in WinPcap didn't do all the checks and error reporting that the current code in libpcap does (I cleaned up the remote capture code a lot when I added it to standard libpcap).
Either 1) there's a bug in libpcap 1.9.1's client code, so that it's rejecting valid rpcap packets or 2) there's a bug in the rpcap daemon in the PABX's software, and it's sending invalid rpcap packets (too short).
Please:
- open Wireshark, and start a capture on the interface for the network between your PC and the PABX, using the capture filter "port 2002";
- while that capture is running, open Wireshark again, so that you have two instances of Wireshark running on your PC, and, in the second instance of Wireshark, try to add remote interfaces;
- when the attempt to add remote interfaces reports the error in the second instance of Wireshark, stop the capture in the first instance of Wireshark;
- if the first instance (the one doing the "port 2002" capture) shows any traffic, please do File > Save to save the raw capture to a file;
- go to the libpcap issues list and open a new issue, and attach the raw capture file to the issue.
