No servers showing on the server list after clicking Multiplayer?
It is most likely an Antivirus causing this problem.
-If you have any known antivirus (other than windows defender) allow the BeamMP Launcher application through the antivirus, if this still doesnt work try disabling the antivirus or deleting it
-If you do not have any antivirus (other than windows defender), try opening “Control Panel” and then going to “uninstall a program” and searching for any antivirus like Avast or McAfee and then right clicking and uninstalling them, even if you find one antivirus continue to check for others as you may have numerous
-Make sure that the BeamMP mod is the ONLY MOD ACTIVE in your mod manager