Set-DnsClientGlobalSetting - throwing "Access to a CIM resource was not available"
Solution 1:
I believe this is because you have a GPO defining the DNS suffix search list.
I was able to validate this in my environment by having a computer in a test OU and test GPO assigned to it with the DNS suffix search list setting disabled. Make sure this test GPO takes precedence over other GPOs that may define the DNS suffix search list.
After ensuring a GPO wasn't defining the DNS suffix search list, this command should as expected.