Use NGINX's Logged Upstream Address to Check IPv6 Reachability
An AAAA answer can be correct while the selected route is unusable; resolver ipv6=off applies only to NGINX's runtime resolver.
Pair the connection error with the upstream address. An IPv6 destination and network-unreachable error suggest an IPv6 route failure even though DNS returned a valid answer. A later “temporarily disabled” message alone does not identify DNS as the cause.
For an existing configuration actually using NGINX's runtime resolver, an intended IPv4-only policy can use:
resolver 192.0.2.53 ipv6=off;Use a trusted, reachable resolver in place of the documentation address. NGINX normally looks up both families; ipv6=off suppresses this resolver's IPv6 lookups.
It neither disables IPv6 on the host nor changes every hostname resolved when configuration loads. Confirm the dynamic destination uses that resolver before expecting a routing change.
If the workload requires IPv6, repair its route instead. A refused IPv4 port, failed parent connection or stale record points to a different problem.