What IP does http://my.channelsdvr.net/ resolve to?
Actually what domain that remaps to for you.
If you have enabled remote access, it resolves to your WAN IP (your home's external public IP).
I know that. The OP needs to set a firewall rule to route the client running channels through the other IP.
For those watching at home, this is bunch of posts about opening a port?
Using a tool could help - e.g. http://ismyportopen.com/
Or just search for "is my port open"
This tells me 8089 is open on the 1:1 IP address. Yet, the app tells me the server can’t be reached. I can still use the web ui though.
Is there another port that needs to be open?
Did you try the firewall rule i suggested? On pfsense in a 1:1 you have to have the private address/port opened on the wan int.
