Originally posted this https://flightsimulator.zendesk.com/hc/en-us/requests/162365 but it was closed and I was pointed here. Note I am not developing against the SDK but these are existing tools. If you have the RealSImGear and AIrManager plugin installed in your community folder then no other sim connect clients (flight events, fs2ff, etc) can connect. If you remove airmanager or realsimgear then you can connect several other sim connect clients. Simconnect should be a multi client protocol so it being blocked doesn't make sense.