Is protocol version is supported by UNET?
If a client uses an outdated version of a game how can i check it on a network level?
We have versioning built into the protocol for the servers we host. The matchmaker and relay servers will check this whenever you talk to them to make sure the interface is proper, no additional work is required on a developers part.
Additionally you can manage your own protocol setup by adjusting the domain member in any request message that goes to matchmaker (CreateMatchRequest, ListMatchRequest, etc). Matchmaker will make each domain a separate set with respect to privacy, so no two clients with different domains will end up listing or joining each other’s matches.
And if I do not use a Matchmaker?
Yes, if protocol version will mismatch you will receive Disconnect event and error will contain protocol mismatch code
Or probably i do not understand your use case? If you talk about your version of the game, so far no we do not support this, but it is good featue, looks like we need to support this
@aabramychev Is this supported now? If so, how?
@ not yet 
this feature will require protocol changing… So I leave this feature to the future with security and ddos prevention. So far you can check version during inGame handshake. I hope it is not very difficult. (Sorry about this news)