Outside mobile coverage

[dawnjoanna44]

When out and about . Can never get any internet connection on mobile phone. Been like this for a few months.

[jonsie]

Do you have an iphone @dawnjoanna44 

if so change the APN to : mobile.o2.co.uk

[MI5]

@dawnjoanna44 

Start by checking for issues here O2 Service Status

Make sure you have mobile data turned on and reset your network settings.

Did you change anything at the same time the data stopped working?

A tariff change, sim change, upgrade etc?

[dawnjoanna44]

Have done this. Able to use network mobile data indoors without WiFi on. Will see what it’s like outside tomorrow.

[jonsie]

Is it an iphone @dawnjoanna44 ?

You can just turn wifi off to check indoors.

[MI5]

Changing the data apn on an iPhone, only works abroad. iPhones in the UK will work off either apn although unless iData is enabled on the account, some iPhone specific features won't work.
Anyway, as data works at home with wifi off, I doubt, if it is an iPhone, that is the issue.
More likely to be changing to a different mast which has issues.