Hi, I have my airplay receiver off but I still get the 'Port 5000 is already in use' message, I have already restarted my macbook a few times and still get the message. I know I can change to another port but this port used to work a few weeks ago when the airplay receiver was off.
Port 5000 still in use
Port 5000 is used for UPnP (universal plug and play) which got implemented into mDNSResponder on your Mac. It's used for Bonjour/mDNS to find AirPrint and other resources on your network, typically mDNS runs on port 5353.
Perhaps blocking 5000 and keep 5353 open is still giving you access to AirPrint, AirDrop and AirPlay resources on your .local network.
Or if not needed, shutting down mDNSresponder might solve your issues.