As we all know, IPv4 addresses in the world are running out soon (just pretend I'm talking nonsense if I'm wrong), so not all ISPs in China have public IP addresses. At the same time, there are many peculiar requirements (such as wanting to play Red Alert online with friends from different locations). To achieve the effect of building a remote intranet, we have to take some special measures to network. In fact, there are many articles about building remote intranets, such as the one by Lemon Rain, titled "Playing LAN Games Remotely - Building a Remote Server Network Quickly with N2N," which uses a software called N2N to establish tunnels. However, when I tried to use N2N for networking, I encountered several problems. First of all, I could only find a version of the Windows client v2 compiled by a network blogger, and it was very slow to download the client from a domestic server.
At one point, I almost gave up and thought about using ready-made LAN gaming platforms (like Hao Fang), but after downloading and registering (this platform actually requires an ID card for registration, which is ridiculous, although I registered with a generated ID card number), I got stuck at the loading screen when trying to log in. Helplessly, I had to see if there were any other solutions available.
Upon the suggestion of a friend who really wanted to play Red Alert 3, I researched the solution called ZeroTier for remote networking and found it quite convenient.
But here's the problem: after I started using ZeroTier, the tunnels were established, but for some reason, two nodes couldn't ping each other.