I set the primary dns on my fritzbox with the ip of the pi hole and 1.1.1.1 as secondary. Content blocking works fine
Then I went to the local dns section and configured hub.lan to point to a working ip address. When I try to use http://hub.lan the browser returns me
DNS_PROBE_FINISHED_NXDOMAIN
I checked with ipconfig /all the dns used by the pc and it is correct.
Don't do that.
The word "secondary" is not the best choice for DNS and is misleading. The idea of "redundancy" doesn't apply in this case.
If you have 2 DNS servers configured on the router, both will be used concurrently. Some queries will use the "primary" and some others will use the "secondary".
The problem is: when a device uses the secondary DNS server, it will bypass Pi-hole.