K8s start   Service Kube calico start reports the following error

Skipping datastore connection test
ERROR: Unable to access datastore to query node configuration
Terminating
Calico node failed to start

Solution:

The main reason for this problem is that the firewall of the primary node is turned on. Just turn off the firewall of the primary node (that is, the server where etcd is installed)

systemctl stop firewalld

Other possible errors

1. The address of etcd in calico configuration file is written incorrectly
2. Etcd service is not started