Unable to connect to WireGuard Server on GL-SFT1200 / Opal

I currently have the GL-SFT1200 and GL-MT3000 with a German FritzBox router. I have spent countless hours today trying to set everything up so I can bring my GL-MT3000 with me when I travel outside of Germany to be able to use my home IP address.

I have been following the instructions here - https://www.youtube.com/watch?v=LXbDg1v65Qs&ab_channel=JustinReviewsandRepairs

I have my GL-SFT1200 connected directly to my FritzBox Router/Modem and after enabling DDNS since my internet provider does not provide me with a static IP address, I go to VPN → WireGuard Server → Start → Management and add a configuration. I scan the QR code with the WireGuard app on my phone but after turning it on, the internet on my phone does not work.

This is all while browsing on my cell phone providers network.

I have set up port forwarding on the Fritz Box by choosing the GL-SFT1200, UDP protocol, and 51820 as the port to share. I am sharing a photo of the port forwarding settings on my router.

Can someone please help me get my phone connected to the WireGuard server on the travel router? From there, I can diagnose what is wrong so I can connect the GL-MT3000 to the GL-SFT1200 WireGuard server. Thank you.

Currently, there are some problems with the use of FritzBox, We are checking it.

Will enabling “Permit independent port sharing for this device” work?
Also, the Peer Endpoint for the MT3000 wireguard conf file should be public IP address of your FritzBox.