So i have tried of couple scenario which work and not work:
1. Host and player both using Wifi to connect, works can see each other and can join room
2. Host using wifi, player using mobile network, player can see the room but once joinining, it keep establishing connection until it timed out
3. Host using wifi, player using mobile network with VPN, same as result as Scenario 1
So it seems mobile network seems to be buggy, but the other day when we try using Wifi on host and Mobile network on player it works, is there a reason for this or something i am missing?