Is the sessions freezing and then resuming or being disconnected?
A freezing session is due to a communication issue between the endpoint and Horizon Agent (If you are doing any tunneling it could also be between that device). This can be due to a network communication issue (latency/packet loss) or high utilization on the guest or host that is causing a communication issue (latency/packet loss).
If the session is being disconnected along with that error message it's due to someone logging in with the same username from a different endpoint.
