Issue
Users are unable to join a SteamCMD hosted server for games such as ‘7 Days to Die’
Cause
There are some reported issues with the ‘SteamNetworking’ protocol which may be preventing the connection. Also, the ‘EAC’ option is also known to cause connectivity issues for some users.
Resolution
Under ‘My Servers > Configure > Server Disabled Network Protocols’ select ‘LiteNetLib’ then click ‘Save & Restart’ to restart the server:
If this does not resolve the issue you can try disabling ‘EAC’ to see if it helps:
(Source: 7 Days To Die: Troubleshooting | Best 7 Days to Die Server Hosting )