ERR_NAME_NOT_RESOLVED on Android
Why it happens on Android
Android's Private DNS setting forces every lookup through a specified DoT provider; if that hostname is wrong or the provider is blocked on the current network, all resolution fails.
The fix on Android
Settings → Network & internet → Private DNS → set to Automatic (or Off), then retry. Also test on mobile data to rule out a filtering Wi-Fi network.
Is ERR_NAME_NOT_RESOLVED happening on your domain?
Resolving the name from outside your machine shows whether public resolvers can find a record, helping distinguish a public DNS issue from a local resolver or network problem.
Free, no signup. Runs from outside your network, which is the only way to tell a server fault from a local one.
If that didn't fix it
Android has its own failure mode, but ERR_NAME_NOT_RESOLVED has a wider set of causes that apply everywhere. The most common one overall is: no dns record exists for the hostname.
All causes and fixes for ERR_NAME_NOT_RESOLVED