But I dont think any of these is very important and its not the main reason why people cant connect. Its battleye. I was kicked twice while trying to join for client not responding. I dont have problems with that usually.
So either he is running very old version of BE server, or BE is blocked by firewall and it cant initialize, but I rather think its the first issue.
Other than that you need to work on your network performance, since it took me forever to load you mission and download it. First fix battleye though, lots of problems may come because od it not working properly.