> I know how to do that with a computer but not iPhones. Androids are probably easier to set up.

I don’t understand this type of comment which is so prevalent on HN. If you don’t know, why do you assume something else is easier or harder? It takes less time to do this web search than to reply to a comment. Here’s how to change it on both iOS and Android, from the same website:

https://www.howtogeek.com/261701/how-to-change-the-dns-serve...

https://www.howtogeek.com/787039/how-to-change-your-dns-serv...

Doesn’t seem meaningfully different to me.

You can install an app like 1.1.1.1 to use Cloudflare and there are many apps that will do it for generic DNS. Or manually but you will need to create DNS Profile and install it. It is not hard to generate one, but it is usually used for encrypted DNS which you should be using anyway.

There’s no setting for mobile data, but for WiFi you can go into the network settings and override DNS.