Lightroom screens remains blank and says I'm not connected to the internet

I have recently downloaded the new Adobe lightroom program. Opened up the app and i'm getting an error message saying 'not connected to the internet, error message 20400'. See below. 

I'm connected to the internet and all my other adobe apps work fine. I've tried signing out from lightroom, with no success and get the error message above. I've uninstalled and installed the app again, with no luck.

The app works fine on my Ipad, so it's nothing to do with my account. 

If anyone can help, please let me know as trying to get through to any adobe support is near impossible. Thanks