Whenever I try to log in the game using mobile data I get an error, I've spent the last few hours trying to find a fix to no avail. It was playing fine yesterday but it was likely that an app updated involved with/or Pokemon GO.
I use a Huawei Signal disappears when I load Pokemon GO
What have you tried so far @Deepkalsi
You could try a couple of things
From the home screen, tap the All Apps icon.
Scroll to and tap Settings.
Scroll to and tap Manage apps.
Tap the All tab.
Scroll to and tap the preferred application.
Tap Clear cache.
What APN do you have stored?