Other Apps work but not IP Cam Viewer

[SuperTurtle]

Hello,
I have an HIKVision OCB-7208HQHI-K1 DVR
Selected MODEL is Hikvision DS-72xx Series
Using paid version of IP Cam Viewer Version 6.7.7
IP Cam Viewer works on WiFi
IP Cam Viewer will not connect from outside the network (However, other apps with same settings will)
Currently using Guarding Vision App (works External and Local/Internal WiFi)
I tried the Scan function but no compatible models were found.

At this point I'm not sure what to try.
As mentioned, I can access the video streams from other apps just fine so that verifies the port is properly forwarded and the streams are available.
Sometimes I get an error message that the PW/UN is incorrect, but I verified they are
Usually I just get the message "Camera Feed Not Available"

Is it because the Model Hikvision DVR I have is not fully supported? This seems to be a modern version of older Hikvision DVR's. Will support be added?

Thanks,
SuperTurtle

[N4Spd]

if it works on wifi, then it's just network configuration to work in WAN. not app issue.

see: https://hit-mob.com/ip-cam-viewer-android/faq/#2