I believe the problem might be that your router firewall is blocking the connection for your channels (also can be windows firewall/antivirus, before trying to port forward. Disable your windows firewall and antivirus to isolate the problem. If it persists, then thats not the problem.
To port forward, its dependent on your router. The channel start port is 8585 and for each channel it increases by 1 (i.e., Channel 1 = 8585, Channel 2 = 8586, Channel 3 = 8587, ...). Since I cannot tell you specifics for your router, use the link provided, find your router and then port forward these ports you are using for channels.
This is the port forward page for 3dx, but just dont port forward those ports, do these ones instead.
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