This error (as it says) is usually a connectivity issue and not a problem with TLS configuration.
I would be inclined to think that you configured the server yourself and perhaps didn’t allow for proper incoming traffic. But we can rule that out since you said that the VPN works successfully from your host. (You tested it just now I hope?)
The config files look ok.
(IIUC You should uncomment at least
LOCAL_NET="\ 127.0.0.0-127.0.0.255 \ 10.152.152.0-10.152.152.255 \ "
This shouldn’t prevent you from connecting to VPN though.)
The only thing I can think of now is to test network connectivity from your Gateway.
curl.anondist-orig will bypass Tor so it’s safe to use even if you’re trying to hide Tor usage. This command returns your real IP - don’t post.
In a Gateway Terminal:
(or if it’s safe to connect to torproject.org, you can use:
curl.anondist-orig -H 'Host: check.torproject.org' -k https://126.96.36.199 | grep IP)
(Since you edited 50_user, have you rebooted the Gateway or Reload Firewall?)