According to KB article 811889:
Because you might not use a domain administrator account to run the
SQL Server service (to prevent security risk), the computer that is
running SQL Server cannot create its own SPN. Therefore, you must
manually create an SPN for your computer that is running SQL Server if
you want to use Kerberos authentication when you connect to a computer
that is running SQL Server.
In the same article, there are several options to remedy this problem. I would try creating an SPN manually.
To manually set up an SPN for SQL Server, refer to KB article 319723 (excerpted below), where it is recommended to use the
ADSIEdit tool on the domain controller. Scroll down to Step 3: Configure the SQL Server service to create SPNs dynamically on that article.
You have to modify permissions to allow
Read servicePrincipalName and
Write servicePrincipalName for the SQL Server service account, and it's quite convoluted.
For what it's worth, sometimes deleting a server name from there gets SPN to work, too. Good luck!
The steps from KB 319723 (archived) are:
- Click Start, click Run, type Adsiedit.msc, and then click OK.
- In the ADSI Edit snap-in, expand Domain [DomainName], expand DC= RootDomainName, expand CN=Users, right-click CN= AccountName , and then click Properties.
- In the CN= AccountName Properties dialog box, click the Security tab.
- On the Security tab, click Advanced.
- In the Advanced Security Settings dialog box, make sure that SELF is listed under Permission entries.
- If SELF is not listed, click Add, and then add SELF.
- Under Permission entries, click SELF, and then click Edit.
- In the Permission Entry dialog box, click the Properties tab.
- On the Properties tab, click This object only in the Apply onto list, and then click to select the check boxes for the following permissions under Permissions:
- Read servicePrincipalName
- Write servicePrincipalName
- Click OK two times.
- In the CN= AccountName Properties dialog box, click Attribute Editor.
- Under Attributes, click servicePrincipalName in the Attribute column, and then click Edit.
- In the Multi-valued String Editor dialog box, remove the service principle names (SPNs) for the instances of SQL Server that use this SQL Server service account.
- Exit the ADSI Edit snap-in.
NOTE: these steps are included for reference as the original KB page has been taken down. Important context & informative notes exist on the linked snapshot that are not excerpted here.