Hi,
I'm using two sims and the data is enabled on the second sim. Sometimes I need to connect to FON networks, that require login before giving internet access. The problem is that the login page is not working unless I disable the mobile data (forcing the phone to use the wifi). Is there any workaround?

Fon networks are wifi networks: to connect to them you'll have to switch on your wifi module, and this disables the mobile data network.
It's all normal!