DNS_PROBE_FINISHED_NXDOMAIN on Android
Why it happens on Android
Android caches negative DNS answers aggressively and Private DNS (DNS over TLS) silently fails when the configured provider cannot resolve the name.
The fix on Android
Settings → Network & internet → Private DNS → set to Automatic, then toggle airplane mode to clear the cache. Test the same domain on Wi-Fi and mobile data to isolate the resolver.
Is DNS_PROBE_FINISHED_NXDOMAIN happening on your domain?
The DNS lookup queries public resolvers directly and shows the A, AAAA, CNAME and NS records that actually exist — which instantly separates 'record missing' from 'my resolver is stale'.
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 DNS_PROBE_FINISHED_NXDOMAIN has a wider set of causes that apply everywhere. The most common one overall is: the a or cname record for the hostname does not exist.
All causes and fixes for DNS_PROBE_FINISHED_NXDOMAIN