PC + Wifi + homeserver
-> router (Fritzbox)
-> UPC cable box
I have 2 NAT after each other.
I have a strange DNS problem. I configured DuckDns to point to an internal IP address. Resolution works everywhere, but not in the devices connected to the Fritzbox. Here there is a timeout when the DuckDns entry points to an internal IP like 192.168.x.y.
If the Duckdns entry points to a "real" IP, the resolution works correctly.
Then I switched the DNS in the Fritzbox (config menu -> dns server) to 9.9.9.9, however I get the same result. Something does not work as expected, because:
nslookup xx.duckdns.org: timeout
nslookup xx.duckdns.org 9.9.9.9: can resolve
It seems that the Fritzbox suppresses DNS lookups, when they return an IP which is inside NAT.
Is this plausible?
How can I find out which DNS is really used when Fritzbox is doing the resolution?
Greetings, exae