Hi,
I enabled back to home on the router with all default rules/settings and created few VPN peers. Few of them have option to access local network.
I am trying to host a Stardew valley server on one of the phones connected via Wi-Fi and then trying to access it through another phone, which has 4G and enabled BTH VPN. It doesn't work.
I tried to run a webserver on one of the PCs connected locally and then access it from the BTH phone and it worked.
Does it only allow TCP protocol by default?
Hi,
You've actually gone down the proper path: hosting a game server is a typical application of VPNs. Wireguard/BTH is one of those that can yield excellent performance for these purposes. (The other usual choice being ZeroTier.)
What you should carefully consider is that both solutions provide for the possibility of direct connections and connections that go through a relay. Going through a relay should not be considered a proper solution, because it will severely limit bandwidth and add significant additional latency.
What you describe, i.e. running a local server and having access to it through VPN generally should Just Work(tm). As you experience, it commonly doesn't. This generally comes down to the integrated firewall on the system that you're operating your server on. Many devices (Windows, usual phone OS-es) apply a firewall to incoming connections that default to only allow them from the subnet they have obtained an address from, which for a connection incoming from a properly configured routed VPN is of course different.
So the failure to access the game server run on a phone probably has nothing to do with wifi, but probably related to the configuration of the server device. There is also nothing that would inherently allow TCP, but not UDP in the usual way of implementing VPNs. (Although there is always a possibility to apply specific filtering.)
The solution to this firewalling problem is usually the appropriate configuration of the server firewall, as it is done on the given OS. An alternative is to give local addresses to the external (connected via VPN) hosts, which can be done in your Mikrotik.
As a note, running any sort of server over wifi is heavily non-optimal. The presence of a wifi connection can be felt even on not-exactly-interactive connections (such as a web server) and having one on both ends of a connection is felt doubly.
If the web server works over the VPN but the game doesn't, I'd also assume the VPN itself isn't the problem. Many games use different ports, protocols, or local network discovery methods that don't always work through a routed VPN without additional configuration. It's worth checking whether the game actually supports direct IP connections as well. I ran into similar networking quirks while trying different multiplayer titles. For something less dependent on network setup, I've also spent time with chicken road game casino. The Chicken Road game casino experience is much easier to jump into, and the crash gambling format doesn't require dealing with VPNs, firewall rules, or complicated hosting just to have a quick gaming session.