Cluster registration problem

I have an HA setup of Rancher 2.5.5. Then I create a K8S cluster using RKE. When I try to import this cluster into rancher server, the progress get stuck. Here is the log of the ‘cluster-register’ container:

[ywb@k8s-master ~]$ kubectl logs cattle-cluster-agent-787644b4b5-6rbsr -n cattle-system

ERROR: is not accessible (Could not resolve host: …)

It’s clear that the server URL cannot be resolved. How can I fix this? Do I need to add a DNS entry pointing to ‘’ somewhere?

Yes, the server URL is how the agent reaches the server and has to actually exist and resolve/route to a server container.