Unbound periodically stops resolving some hostnames

[vrtigo1]

What do you have under DNS server options on the General page?

Under system > settings > general > DNS servers I have 1.1.1.1 and 8.8.8.8.

Not DNS servers.  DNS server options.  The section below where the DNS servers are entered.

Nothing checked there.

That's what I figured.  Right now you have Unbound operating in resolve mode which hits the root servers.  I assume you want it to be working in forwarding mode and using 1.1.1.1 and 8.8.8.8.

On Services: Unbound DNS: Query Forwarding check the Use System Nameservers checkbox.  If you prefer to use DoT, you can set that instead but then I'd recommend removing the entries from the General tab.

Is there any reason I want to use forwarders vs root servers?  I can understand forwarders would be necessary if I wanted to use a filtering service like OpenDNS, but failing that aren't all DNS servers designed to use root hints?

[CJ]

Is there any reason I want to use forwarders vs root servers?  I can understand forwarders would be necessary if I wanted to use a filtering service like OpenDNS, but failing that aren't all DNS servers designed to use root hints?

Designed to use root is different from whether or not you should use root.  If everyone used the root servers it would overwhelm them.  That's why caching forwarders exist.

In your case, Unbound is attempting to contact IPv6 root servers and that's why you're having resolution failures.

[vrtigo1]

Is there any reason I want to use forwarders vs root servers?  I can understand forwarders would be necessary if I wanted to use a filtering service like OpenDNS, but failing that aren't all DNS servers designed to use root hints?

Designed to use root is different from whether or not you should use root.  If everyone used the root servers it would overwhelm them.  That's why caching forwarders exist.

In your case, Unbound is attempting to contact IPv6 root servers and that's why you're having resolution failures.

This behavior seems like a bug if the system and Unbound are both configured to not use IPv6.  Do you know where this should be reported?