My Macbook has stopped me connecting to BT hub

Hi,

I used to be connected to BT Hub but all of a sudden about a month or two ago it stopped me connecting.

I can still connect to BT WiFI with FON but I have to log in every time ( even when I just leave the macbook for a few minutes.)

This morning I did manage to connect it for a few minutes but eventually it stopped and when I retried it told me that the IP address would not be able to connect to the internet.

Anyone any ideas?

P.S.

Now its connected automatically all of a sudden. What is going on?