I've found out that photon plugin doesn't work with secure connection (https://) but works with (http://) because its connection is (ws://) which should be (wss://) if you are using a secure connection. That's how it worked on my HTML5 game.
My android version on the game with photon plugin seem to have the same problem probably because of a secure connection.
Note that I'm using the free licence of photon engine.
Can some one help me on this?