Hello!

I couldn't find any good answer about this topic, so I decided to make a new discussion.

How do one connect to a client-hosted game reliably?

In co-op games, making a dedicated server looks like an overkill, but I need to reliably connect 2 peers together.

My game is server-authoritative, not full P2P, but nowadays almost nobody knows how to port-forward, since AAA titles somehow do it manually.

The question is, how? Like in Borderlands, I just click on "go online", and suddenly others see my game online, and can join without any problem.

I have a self hosted lobby service( working with database ), the matchmaking is covered, the problem starts when it comes to directly connecting to an IP address.

I'm currently using RakNet for networking library, which I feel is a bit overkill, because I don't use any of it's high level features, only connecting-packet sending and receiving.

I've tried RakNet's NAT punchthrough, but that's not reliable enough. Often it gives punchthrough failed, which customers don't understand and claiming it's the game's fault that they can't connect, because Diablo 3 works. I, as a developer, of course I know what's the difference, but what can I do to fight this problem?

Is there any middleware solution you know of? How do bigger titles handle it?( like torchlight, borderlands, and other coop games )

I'm even open for paid services, libraries, anything.

Thank you

Edit: I'm using C++, and a self programmed engine

For high-quality solutions (Xbox Live, etc,) there is also a fallback where the matchmaker will forward data to users for whom punch-through doesn't work.

Exactly what we've done on all the major online-component games hosted by the client.

The lobby/matchmaker server will act as an introducer, which usually works. A set of extra servers (geographically scattered and chosen based on communication time) act as repeaters if the mesh cannot be established.

There are many potential reasons why a game mesh cannot be created, such as multiple people behind a single NAT that doesn't support hairpin, nested NATs that don't handle punch-through well, ISP-rules that decide an IP address is untrustworthy for some reason like VPNs or open relays or TOR exit nodes or whatever else.

If you're already paying for lobbies and servers and your game's bandwidth needs are low, adding some repeaters are only a small additional effort and cost. If your bandwidth needs are high, however, it could quickly have painful costs.

Thanks for the answers :)

Problem is, the bandwidth isn't low, and low ping is needed. For these reasons I don't really trust in forwarding services.

It's a fast paced action RPG game, with many units moving around.

If the matchmaking is just connecting random people together then raknet's punchthrough (possibly combined with raknet's uPNP port opening) would suffice, I think. Some would fail, but that's fine because users just try again, and it might work next time (especially if your matchmaking server tries to avoid repeatedly connecting the same pairings).

Aaand that's when "this game's netcode sucks", "they cant even make multiplayer", "netcode is horrible" reviews coming.. :(

So basically, there is no way to guarantee the connection, only if there are official dedicated servers.

Thanks for the help, that clarified things for me.