Knock outs on iOS

We're using recent version on photon with unity 5.5.0f, compiling with IL2CPP for iOS. During the game players can suddenly receive OnRoomLeft, and while debugging with XCode we see:

-----------------

Receiving failed. SocketException: WouldBlock
UnityEngine.DebugLogHandler:Internal_Log(LogType, String, Object)
UnityEngine.DebugLogHandler:LogFormat(LogType, Object, String, Object[])
UnityEngine.Logger:Log(LogType, Object)
UnityEngine.Debug:LogError(Object)
NetworkingPeer:DebugReturn(DebugLevel, String)
ExitGames.Client.Photon.<>c__DisplayClass147_0:b__0()
ExitGames.Client.Photon.MyAction:Invoke()
ExitGames.Client.Photon.TPeer:DispatchIncomingCommands()
ExitGames.Client.Photon.PhotonPeer:DispatchIncomingCommands()
PhotonHandler:Update()

(Filename: /Users/builduser/buildslave/unity/build/artifacts/generated/common/runtime/DebugBindings.gen.cpp Line: 51)

OnLeftRoom
UnityEngine.DebugLogHandler:Internal_Log(LogType, String, Object)
UnityEngine.DebugLogHandler:LogFormat(LogType, Object, String, Object[])
UnityEngine.Logger:Log(LogType, Object)
UnityEngine.Debug:Log(Object)
Mintfrogs.Kepler.Photon.GameManager:OnLeftRoom()
UnityEngine.GameObject:SendMessage(String, Object, SendMessageOptions)
NetworkingPeer:SendMonoMessage(PhotonNetworkingMessage, Object[])
NetworkingPeer:LeftRoomCleanup()
NetworkingPeer:OnStatusChanged(StatusCode)
ExitGames.Client.Photon.<>c__DisplayClass148_0:b__0()
ExitGames.Client.Photon.MyAction:Invoke()
ExitGames.Client.Photon.TPeer:DispatchIncomingCommands()
ExitGames.Client.Photon.PhotonPeer:DispatchIncomingCommands()
PhotonHandler:Update()