IPhone LAN Gaming Over Windows VPN? (UDP Broadcasting)

I’m trying to play an iPhone game that uses WiFi to create local games for other iPhones to join. The way it works is one player starts a game and becomes the host over WiFi and it gets broadcasted to other players on the network to see the game and join. If the host leaves the game the current game gets shutdown and all clients get sent to the lobby, but clients can connect and disconnect how they want.

My problem is that I believe the UDP packets are not being broadcasted to other iPhones over the VPN network I’m using to play with my friend who lives far from me. When connected to the Windows VPN server he has running on his laptop, I am able to ping every device on his network, including my iPhone from his laptop. I just do not see the LAN lobby game, and neither can he see mine. I believe this has something to do with the subnet. From what I’ve read, VPN does not put me on the same subnet as him where the UDP packets are being broadcasted, or maybe they’re even being dropped completely in the VPN. The strange thing is, when I am physically on his network and connect through VPN, I have no Internet access and he cannot see my game, but I can see his and connect fine.

I’ve used WireShark to track down the packets being sent and received, and the one thing I noticed is that the UDP packets are almost always being sent/received on different ports. I thought they would be hard coded into the game of which ports the packets should be sent/received from but the origin ports usually range 50000–59000 and the receiving ports range from 9000–9999, and are usually different with every LAN game.

The problem I’ve run into is I want to keep this simple on the iPhone side so that non-techy players can join in on play over VPN without having to hack around with external programs or anything. My goal is to setup a dedicated VPN server for me and my friends to play together on daily. I don’t care how complicated it has to be on the VPN server side to get it working, but I want it simple on the iPhone side and be as simple as plugging the correct VPN server details into the built-in iPhone VPN tab.

I want to stay away from Hamachi, Tunngle, etc because I don’t believe they’re ideal for iPhones as far as the built-in VPN functionality goes. I’ve been suggested using a network tap to get UDP broadcasting to all clients on the server but before I spend any money I want to conclude that this in fact is my best bet. I’ve also read about bridging. I have no idea what my next step is to get this working. I have no problem buying equipment to get this working, just please point me in the right direction.

To sum it all up in one question: How do I get UDP broadcasting on a Windows VPN to work iPhone-to-iPhone?