Xbox Series X can't connect to mobile broadband (Static IP issue)

Hi, would appreciate any help on this as I'm close to banging my head against the wall.

I have an Xbox Series X and received Three 5G hub at the start of the month, worked fine with an ethernet cable for over a week and a half with no issues.

Now, I just cannot connect to the internet on it. The error I usually get is "Cannot connect using static IP address" but I've been told the hub doesn't support static IP do I don't know why it's trying to get a static IP, my settings are set to auto on the console.

Though, the IP address is always set to 0 when I log on which feels like the auto setting is being overridden and it's being set at manual? As when I then change the IP to auto I can see the IP address increasing eery second, it sort of flickers and changes. Is this an Xbox issue, or an issue with my ISP?

I can connect the Xbox wirelessly with both my phone hotspots. I just cannot connect wired or wirelessly to the hub.

I genuinely have no idea what to do now. All my other devices bar my Windows laptop can connect fine, and I don't know whether at this point to just return the hub if I can't fix it.

:)