Travel bolt on not workin, no data in USA

[VantageUK]

Hi all, 

UK resident just landed in LA last night. Received the text from O2 saying my travel £6 per day plan is active but it's not working. Connected to AT&T but I'm getting no data, no 5g, 4g, nothing. Relying on WiFi. The 5g symbol flashes up ocassionally but disappears. 

O2 chat was no help, just said to phone them but I can't as no data. Or for whatever reason I can't make any calls even with wifi calling on. 

I can see under settings in the mobile data network tab there's a reset settings button though scared to hit that as there looks to be all kinds of info and passwords i know nothing about.

Can anyone offer any advice?

I should add this bolt on has worked perfectly fine for me last year in LA and Dubai.

Many thanks

[VantageUK]

Ah I just solved the problem! Had to change the APN to mobile.o2.co.uk - it was virginmobile before. Guess it got messed up when Virgin switched to O2. 

Might want to let people know though O2!

[MI5]

@VantageUK 

It's what we have been advising here for a long time already.