Yes. Since it's not showing up in LAN, you may need to unblock the ports on your computer's firewall (on the computer, not the router). Once you do that, have them try via LAN again.
To figure out what port your Blockland uses, type this into console:
echo($Pref::Server::Port);
Then go into your computer firewall (Windows Firewall, etc) and add an exception for whatever port the console told you in the previous step.