I have been messing around with UAVcast for the past couple of days, and have notice in the past two days a problem connecting to my UDP stream, when I first connect to my VPN which keeps static IP addresses for all nodes and I have made sure that UDP ports 5600, 14550 are open on my windows 10 firewall, all apps show a online status in my VPN with their static IP, usually if I restart my PC and connect using UDP it will automatically connect but if I disconnect and try reconnecting I usually get this message or a message about socket already being in use? Here is a screen shot using the most current beta version of MP at (12/13/2018:2200MDT). I know it cannot be a connection issue with my VPN as I can remote access all systems from SSH using their IP addresses from zerotier.
when you open MP, it checks port 14550 for inbound udp. if it detects it, it will connect. it does this for 30 seconds.