I have a similar problem on MP4 Pro Trial version 4 Beta 3 Pro. I can connect from my main pc (primary) --> laptop (secondary) fine. but every time that i open the KVM pc it would fail on connect protocol error 3. however, if i reverse the roles of the main pc and laptop, where laptop is primary and main pc is secondary, it works great. but this is not my use case; i need the PC as the primary and laptop as secondary.
wanting to purchase a license for pro version, but i'd rather wait until a patch is pushed out to the general users.
any help from the developer would be wonderful
laptop: windows 11 version 23H2
PC: windows 11 version 22H2
MP4 on both machines: MP4 Pro Trial version 4 Beta 3 Pro