on 08-01-2019 12:55
If not then it sounds as though you are connected to the network but don't have a correct APN (access point name, the settings for the phone to use data).
The link below should help:
on 08-01-2019 12:56
There may be a problem with a mast nearby. Check your status here
Other help in this guide https://community.o2.co.uk/t5/How-to-Guides/How-can-I-sort-out-my-network-issues/ba-p/1014088
Best of luck and welcome to the forum
on 08-01-2019 13:16
@Pav check in settings that those apps are allowed to access mobile data.
OnePlus 6 (O2 & Sfr), Z3 Tablet (Three UK), iPhone 8+ (EE)