BroadcastNetworkFailure : Your connection to the host has been lost.

I'm getting this error often when I leave a multiplayer match and try to rejoin.  It doesn't happen every time.  When I leave the match, DestroySession says it succeeded every time.  And then it has no problem finding the match - but when I try to connect, I get this error. 

Error: UEngine::BroadcastNetworkFailure: FailureType = PendingConnectionFailure, ErrorString = Your connection to the host has been lost., Driver = PendingNetDriver OculusNetDriver_2147481580

[2020.05.04-21.53.40:239][381]LogNet: Warning: Network Failure: PendingNetDriver[PendingConnectionFailure]: Your connection to the host has been lost.

Does anyone know what causes this?