When a session shows up as "ErrorPreparing" it means that the issue is not with connectivity but rather the preparation of the session ("Provisioning" phase, before "Connection").
Sessions under this failure category appear with an "ErrorPreparing" status. If you hover the mouse over the session's date/time, it will show the session's unique token ID, as shown below:
For this type of errors, the first log to look at is C:\RemoteAppPilot\Logs\System.log on the relevant server. Open it and look for this token ID. Then, follow the thread ("TID") (in this case TID=8):
Lines with a star "*" or mentioning an "exception" are usually indications of something going wrong:
Such information can either indicate an unexpected server behavior or a Cameyo service bug, which can be transmitted to Cameyo's development team.