Hi,
DDNS should work with WAN connection too, just use Public as IP Address source and Wired as your Network.
If you want other alternatives to reach your devices behind LAN, you can try using VPN (ZeroTier would be my suggestion as it is easy to configure and to use).
Also, if your devices in LAN have some kind of HTTP interface and you want to control it when you're outside the local network - you can use our RMS platform, it will let you reach any LAN device and its user interface. Additionally, you will get access to your router without public IP and have its information gathered in the RMS platform too.
EB.