Issue:
A/T series and EBD camera cannot use Port Mapping to do a WAN connection.
Solution:
If you use A/T series and EBD camera with Port Mapping, it is allowed to turn on UPnP on your router. Here is a sample via link.
https://tunecomp.net/upnp/
Reference:
[ UVS - 202005064002 ] TVD8701 F/W v1.02 Port Mapping inactive, UPnP
[ EVS - 202003195001 ] ABL4712, port forwarding