Regarding the article
https://www.ispreview.co.uk/index.php/2020/03/covid-19-o2-uk-zero-rates-data-usage-on-help-websites.html How does O2 make this work? Do they know the many IP addresses of all these websites’ servers -no, presumably, especially because if CDNs. Are they snooping on your access then, pulling metadata from your traffic ? And I wouldn’t be happy about them snooping at L4, at the http level.
Hopefully then you’re using a VPN so as to prevent such possible O2 snooping. You could say a good reason not to use O2 otherwise?
My wife uses EE on her iPhone. Perhaps I need an iOS VPN software component on that machine then?