Remote Access iPhone Channels App Connection Failure

I can access my.channelsdvr.net over cellular from iPhone. Then from the Channels app (still connected over cellular) I select Connect to Channels DVR->Away From Home and I get message "Your Channels DVR Server at home can not be reached. Remote access is enabled, but we can not reach your server...". I checked https://check-host.net for (my public IP):8089 TCP port and that looks good. Any idea why the channels app won't work remotely in my scenario?

I had this set up on mine and my wife's cellphone. It might have started working on her phone. However it seemed to be connecting remotely even when she was on home wifi. Anyway, my DVR server (old computer) was really bogged down so I had to disable remote connection. It's not a big deal. The main reason I wanted to connect remotely was to be able to schedule a recording when I'm out (e.g. forgot to set up a recording for a sporting event). It'd be great if that feature could be set up to work even through an intermediate Channels server without having to go through the whole port forwarding business. Thanks for a great product!