I have a home network with an internal DNS resolver. I have some subdomains (public) that maps to a real world IP address, and maps to the home server private address when inside home.

In short, i use unbound and have added some local-data entries so that when at home, those subdomains points to 192.168.x.y instead.

All works perfectly fine from Windows and from Linux PCs.

Android, instead, doesnt work.

With dynamic DHCP allocation on android, the names cannot be resolved (ping will fail...) from the android devices. With specific global DNS servers (like dns.adguard.com) of course will always resolve to the public IP.

The only solution i found is to disable DHCP for the Wifi on android and set a static IP with the 192.168.x.y as DNS server, in this case it will work.

But why? Aynbody has any hints?

It's like Android has some kind of DNS binding protection enabled by default, but i cannot find any information at all.