The LAN DNS under Network Config does not allow you to use the ".internal" domain name.  When attempting to make a new entry, the message "Enter the valid domain name. For example, www.omadanetworks.com." appears.  In 2024 the Internet Corporation for Assigned Names and Numbers (ICANN) officially reserved the top-level domain “.internal” for private network use.  This needs to be fixed in the controller firmware.