Firmware upgrade fails for certain endpoints

Last Updated : Jun 10, 2026 |

Condition

When using the Utility Server, the firmware upgrade fails for certain endpoints, such as 9611, 9621, or 9640 phones.

Cause

DHCP option 242 does not have the TLSSRVRID parameter set to 0. In this case, some endpoints cannot:

  • Fetch settings files and firmware from the Utility Server using HTTPS.

  • Generate a certificate file that uses the Utility Server IP address as the Common Name (CN).

Solution

Procedure

On your DHCP server, set TLSSRVRID to 0 for DHCP option 242.

The following is an example of the DHCP option 242 configuration: TLSSRVR=10.103.1.39, TLSPORT=1543, TLSSRVRID=0.