Multiplayer not working if using mobile network

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?

Welcome to Internet networking. It's complicated. See the multiplayer tutorial which covers this.

Just to chime in with a real-world scenario of networking being a pain.

As a person who relies on a 4G network for the bulk of my connectivity - the NAT type of a mobile network is often restrictive in general and it's not a Construct issue. For example, if you want to play multiplayer games on the Nintendo Switch you cannot use a 4G mobile network because the NAT type is incompatible.

Plenty of other AAA games also have warnings about functionality not being quite right if you're using a Strict NAT type as is the case on mobile data - Destiny 2 is a prime example of this.

A lot of people have complained to the major providers here in the UK at least (particularly those like me who would want to use 4G for their entire home network) but so far they're not interested in changing.

Multiplayer works locally only, to the best of my knowledge, it will never work as you are asking it to. (there must be some cross domain CORES type issues or similar, which I could never figure out a work-around)

Photon has a plugin for C3 that does work and is free for limited use and testing.

construct.net/en/make-games/addons/534/photon-engine-c3

photonengine.com

[The drag drop feature for plugins...whomever came up with that was brilliant. Thanks!]