Last week I was in the UK and the UK mobile network is … weird.
I have no idea but for some reason on SOME of the cell towers I didn’t had connectivity without VPN.
My wife has the same carrier as I have and didn’t encounter those issues. Also, it’s not everywhere, it’s just on some of the cell towers. I didn’t had noticeable issues while traveling, but in the hotel I couldn’t access the internet while my wifey could. Outside it was also not working, but 1-2 kilometer further it was working. At the other side of the town it was again broken.
When traveling back I had one location where it also was not working.
And the weird thing is, that when it was not working, I could connect via my VPN of choice and then it worked without any issues.
I have no idea what’s going on here, but this is just weird.