I have a very similar issue. Seems like Android will bypass your DNS resolver and thus cannot resolve your local names.
I have my home services on "home.my domain.com" accessible from outside and re-mapped to "192.168.0.1" (my internal server IP) at home, and all PCs can access it while all android phones can only resolve to the public IP.
I feel it's something related to DoT or similar but haven't yet dig in that.