Every time I disconnect from wifi I get a notification from android system saying I may be out of data from O2 (service provider) even though I have 25 gigs of mobile data. Tried restart but didn't work. Occasionally it won't give notification and phone works fine, but when it does give notification all aps say offline even though system icons say connected to 4G.Not certain if this is the right place to ask this but does anyone think they have an answer to what I can do to fix this ?