TL;DR: To enter a static DNS server in the BMC web interface, first turn off the "Use DNS servers" toggle for the interface. Despite its name, that toggle enables DNS from DHCP and keeps the manual DNS field locked while it is on.
Recommended action:
Log in to the BMC web interface.
Go to Settings > Network.
Select the network interface you are configuring (for example,
eth0).Locate the Use DNS servers toggle and turn it OFF. This step is required before the static DNS field becomes available (see the Why section below).
Under Static DNS, click Add IP address.
Enter the DNS server IP address, then click Add.
The static DNS server is now saved and will be used by the BMC.
Why:
The Use DNS servers toggle does not mean "let me enter DNS servers." It controls whether the BMC obtains its DNS servers automatically from DHCP. While it is on, the BMC uses DHCP-provided DNS and the manual Static DNS field is unavailable. Turning it off tells the BMC to stop using DHCP-provided DNS, which unlocks the field so you can specify your own server. A clearer label would be "Use DHCP-provided DNS servers" or "Obtain DNS servers automatically."
Going forward:
The toggle is set per network interface and per protocol — IPv4 and IPv6 each have their own toggle. If you configure DNS manually for both, turn the toggle off for each protocol. Re-check the setting after a firmware update or a factory reset, as network settings can return to their defaults.