If you or your friend is using a proxy, you / they will not be able to join your server. Blockland cannot authenticate a user who is using a proxy, as the auth server stores your proxied IP, and when you join a server, the server will just use the IP you joined with, which is not proxied (I think). Meaning that when the server compares your two IPs, they will not match, and you will be booted from the server.
To fix this, just stop using a proxy. If you cannot bypass your proxy due to security reasons, then you are out of luck.
