vpn remote access internet

Hi, I am trying to create a remote connection to my AX88U. However, on the DDNS page of the router GUI it says the router is using a private WAN IP address, possibly due to Multi-NAT, and that this is not supported by DDNS. iplookup.asus.com provides me an IP address for the DDNS, nevertheless...

Hello all, After having an IPCAM installed (via ethernet, not Wifi) and temporarily blocked all access of internet from it, until I have a more secure way to remote access, via my ISP router (Fritzbox 7590). I wanted to achieve a secure remote access from anywhere on the world on my mobile...