Unity server connection time out

I am making multiplayer Game for android using Unity Networking(Unet) and Third Person Controller. it works fine while hosting the game, movement, and other stuff. but problem occur's when a client joins to my Game.

  suppose in the game we are two players so until 5-7 minute it working fine but after that, it goes disconnect. or I connect more and more players this disconnection time is decrementing.

 I tried to search on google,  unity forum and other stuff but nothing help even I am debugging incoming and outgoing data on the profiler. ![alt text][1] I don't see any unnecessary data is sending to the server.

Please Check Attachment Image for Error. Please Help me Guys i really need your Help :)

[1]: /storage/temp/91329-connection-error.png