Macbook pro not connecting to BT Openzone hotspot

Hi,

I have a Macbook Pro late 2016 and for the last few months I have been unable to connect to BT Openzone. I am a BT customer and have free access to BT Openzone wifi hotspots. However for some reason it connects with full wifi connection (5 bars) to BTWifi-with-FON but doesn't show me the login page for BT Openzone as it used to, therefore not being able to login. Instead it shows me the below page.

I have cleared the cache, used the Develop option to log in as a different device, renewed the DCHP, forgotten the hotspot, tried a different browser (Chrome screenshot below) but with no luck!

I remember in April of last year I used a VPN once but haven't since. I don't know if that may be the cause.

Also my iOS devices connect fine to the same hotspot using the app but just not my Macbook.

Can anyone please help?

Many thanks,

Em.