Only Android failed to use my local BIND server Android 13

I have proved, and will offer any proof needed here of what I am seeing. I have two BIND servers on my LAN that provide local IP addresses for devices. The public versions of those addresses are served by Network Solutions. So when laptops and cell phones are connected to the local WiFi, access to the LAN based mail server is available, and when remote the mail server is found via the Public address. The laptops connect to the same WiFi APs. The local bind servers are manually entered into the settings for all wired and WiFi devices. Local DHCP also has the local BIND servers listed. The laptops via the WiFi find the mail server. However, regardless of the email app (we have tried eight of them) and regardless of the Android Version, we have tried 10, 11, 12 and 13, and regardless of the phone maker (we have tried Acer, Huawei and Sumsung, Android can't "find" the mail server. This is even though, when running IP Tools on said phones, both the mx record is correct and the IP address for the mail server is correct. Plus the phones can ping the IP address of the mail server but fails the FQDN for the server -- the name provided via lookup in IP Tools. How can I fix Android? As of now I have to create TWO mail apps, one for local with the local IP address and one for when off the LAN.