Dave,
I've been using P2ATC networked on a separate PC since 2016. Trying to move from XP11 to XP12 and bottom line the XPUIPC XPWideClient is broken in XP12 and causes a CTD. Apparently the original author is working on a new version, but I'm not hopeful. Have you thought about adding basic sim/dataref connectivity to your XPLink traffic plugin so we can ditch XPUIPC altogether?
Thanks for a great product!
Ken