New Windows 10 PC not connecting in Multiplicity as a slave.

I have used MP for many years. Had no real problems until I recently added a new PC running Windows 10. MP will not connect to this PC except once in about 10 'goes' (ie reboots). I am running the master MP soft on a Windows 7 PC. My other four PC's are;  Windows 8.2, Windows 10 and a Windows 10 Laptop. These all work perfectly. Just this new Win 10 PC, which initially ran OK with MP connection then it failed to connect despite all checks as advised in help pages. Can't understand why this new one fails most times. It is fine if I plug a dedicated mouse and KB into it, but very rarely works with MP alone even if I leave them plugged in.  I am currently trying to set up this new PC to eventually take over as master from this W7 machine but need to know if I will still have problems with MP when I change it over. And if there are any checks to do. All my PC's are running Kaspersky and all Kaspersky settings on each PC are identical, so it's very puzzling.