After updating the printer firmware, without any user intervention, the device hostname is switched to a 'DHCP-<printer IP address>' format.
As an example, a device with an IP address 10.169.2.10 and having a hostname set to 'PrinterABC', after a firmware update, the hostname will change from 'PrinterABC' to ‘DHCP-10.169.2.10’.
Although not a Lexmark issue, a firmware fix is available for this issue in EC xxxxx.051.050 or newer firmware release found in the Lexmark Support site.
Note: The 'DHCP-<printer IP address>' hostname is a valid hostname.
If the issue persists, search for more information related to this issue or contact support for further assistance.