After upgrading from KitKat to Lollipop, I found a number of 2nd Gen Moto G phones were no longer connected to the roaming network. This has fixed the problem after a chat with o2:
1. Settings [drag down twice from the top of the screen then tap the cog top right] > [Wireless & networks] More > Mobile networks > Access point names > [then select mobile web if highlighted - for us "02 Mobile Web"].
2. Settings > [Wireless & networks] Data Usage > [then ensure that Mobile data is on, and check your mobile data limit is okay]. This fixed the problem within 30 seconds.
Alternatively,
1. Settings [drag down twice from the top of the screen then tap the cog top right] > [Wireless & networks] More > Mobile networks > Access point names > [then tap the three horizontal dots - tap "Reset to default"] then turn the phone off then back on again.
Hope this helps.
1. Settings [drag down twice from the top of the screen then tap the cog top right] > [Wireless & networks] More > Mobile networks > Access point names > [then select mobile web if highlighted - for us "02 Mobile Web"].
2. Settings > [Wireless & networks] Data Usage > [then ensure that Mobile data is on, and check your mobile data limit is okay]. This fixed the problem within 30 seconds.
Alternatively,
1. Settings [drag down twice from the top of the screen then tap the cog top right] > [Wireless & networks] More > Mobile networks > Access point names > [then tap the three horizontal dots - tap "Reset to default"] then turn the phone off then back on again.
Hope this helps.