mods
folder of your server, via the Files tab.
Restart your server to load in the new plugin/mod, then go to the Network tab of your panel and create a new port. Copy the created port number to your clipboard.
plugins/voicechat
or config/voicechat
folder, and change the value after port=
to the number you copied. Save the file and restart your server, and you should be good to go!