From what I've seen online, you are only supposed to port forward and open the BungeeCord proxy port (25565), while keeping all the back-end servers private and off the internet for security reasons. However, I cannot access back-end servers via BungeeCord unless the ports are opened and port forwarded through my ISP. When attempting to join the proxy I am hit with this message:
Could not connect to a default or fallback server. Incorrectly configured address/port/firewall?...
Port Forwarding & Firewall Issues
Could not connect to a default or fallback server. Incorrectly configured address/port/firewall?...
Port Forwarding & Firewall Issues