We have tried to correct our NAT type with the instructions from Netduma and used the YouTube clip on the URL too. Our Xbox One X is still having issues. I have a Moderate NAT type and still the annoying double NAT. Nothing seems to be working no matter how many opinions I have tried
Your strict NAT will be causing several issues, so lets get that sorted first of all. Enable UPnP in Settings > UPnP on the Netduma, and make sure no rules are set in Settings > Port Forwarding. Then, put your Netduma in the DMZ of your modem. (To do this, navigate to the Device Manager. Copy the WAN IP address found near the top of the page, then access your Modem interface. Paste that WAN IP address into the DMZ box which is usually found in Security / Firewall settings.)