Unable to ssh to the server after kubernetes clustering is deployed

I have brought up 2 Servers which has Red Hat OS 7.5

Docker and Kubernetes are installed in both the nodes (Master & Node) and clustering were also done successfully. Verified with $kubectl get nodes command and could see both the nodes in the Ready state. I have used Flannel for the pod-network.

But after some time, I’m not able to ssh to both the nodes to do the configurations. But I’m able to ping the nodes. Swap is disabled and I’m not able to corner the issue.

Has anyone faced this issue before?