Anyone did a tracert command on windows to see if you could reach the server ?
Open command prompt on Windows (black windows that give you a flash back of DOS era)
C:\Users\yourusers\ > tracert www.3dxchat.com
The result should look like that :
First, you need to look if you can reach the final destination. The server. The last line of that command should be the 3dxchat server : 18.104.22.168
If you can't reach it, you got a routing problem from where you are and you are screwed. You computer or your internet speed won't save you at all. Only solution is to you a VPN to a location that can reach the server. I know user from part of France got issues for a long time,
Second, you need to look at the time in "ms", if the number are much much higher then me... it might mean that there a lot of latency between you and the server and again, your computer won't help you much on that issue. If you got a really bad internet connection... it might have a impact but it doesn't mean it the case.
If you can't reach the server, the issue is probably broken internet and sadly the dev can't do much beside moving the game to a more available Datacenter.
But if many users from the same region of the world got issue at the same time, I would look at the command I suggest.
You can also Ping and look at the result in MS or if the server is reachable :
You need to look this time at the latency which is called temps in french. The value shouldn't be in the thousand...
And also you might want to look if you are losing packet while communicating with the 3dxchat server.
Hope that post help a little to diagnose the issue that cause that the game is unavailable to some players.