forum.pistar.uk

Where can I find up to date and correct specification of the protocol(s) used by the hot spot to talk to the gateways (IPSC or IPSC2 or what?).
I did find an old document (2015) that described it but looking at the packets I see that there is an extra pair of bytes and a possible error too.

You could join this group and ask around there:

https://dvswitch.groups.io

but I saw a message that says this:

"IPSC2 servers send one additional packet at the end of a data stream that is outside of the protocol spec defined by DMR+ and Brandmeister. It does not affect usability. To date I have had no luck finding out what it is, though Artem at Brandmeister was going to try and look into it. BM has made the protocol open to all, DMR+ considers it their IP and is not interested in publication."

As you can see, this whole thing appears to suffer from a lack of full openness which is not that unusual within amateur radio in my experience.