Aria Operations for Logs 8.18.x
There could be an issue on the Active Directory side where Aria Operations for Logs is not able to communicate with one or more domain controllers.
A simple reboot of the domain controller(s) may be needed to resolve the issue.
NOTE: If you have geo-located or security-restricted domain controllers, you should manually specify the domain controllers closest to the VMware Aria Operations for Logs instance. The entries must be Fully Qualified Domain Names (FQDNs) and comma separated. If you do not specify any domain controllers, Operations for Logs will attempt to connect to any available domain controller, which may result in delayed logins.