Do I have to open ports in my firewall?

If you have a firewall set up then you need to allow access to UDP port 19132.

Note

Do you want to use RCON? If so, then TCP port 19132 also needs to be open.

Note

On Windows, you might get a dialog like this when you first start the server. Click “Allow access” to allow PocketMine-MP through the firewall and allow players to connect.