Steam doesn't like tethering?

[Gti]

I've got The One Plan on Three which gives me all you can eat data and allows tethering but steam refuses to work.
I can enter my password but then it says "password not recognised or problem with connection".

Is Three blocking the connection or steam? Googling turns up threads where people get blocked because their plans don't allow tethering but this isn't the case here.
Would i have to use some sort of VPN to connect? I won't have home broadband until i move into my new place and was hoping this would tide me over.

Steam wasn't set to offline mode i can't even play the games in my library

 

[Gti]

Not quite sure what happened. I was checking my windows firewall settings to see if i had blocked it somehow, did not touch anything as it all seemed to be in order so i tried steam again and after it updated it let me in.

God knows how but thanks for the help anyway guys.