Ensure the server is powered on. 

2. Check Network Route 

Run: traceroute <server-ip> (Linux) 

 Or 

tracert <server-ip> (Windows) 

If it breaks mid-path, there may be a network routing issue. 

3. Test Port Availability 

Use: telnet <server-ip> 22  

Or 

 nc -zv <server-ip> 22 

Replace port 22 with the respective service port (e.g., 80 for HTTP, 3306 for MySQL). 

4. Check Firewall Rules 

On the remote server (if accessible via console), verify: 

Firewalld status: 

Sudo systemctl status firewalld 

Stop firewalld if it is active using below command: 

Sudo systemctl  stop firewalld 

Example: sudo firewall-cmd --list-all 

5. Check System Health (via Console or KVM/IPMI access) 

CPU usage: top or uptime 

Memory status: free -h 

Disk status: df -h 

Look for high load or out-of-memory issues. 

6. Check Logs 

System logs: journalctl -xe or /var/log/messages 

SSH logs: /var/log/secure or /var/log/auth.log 

7. Check for Service Status 

Ensure SSH or other services are running: 

systemctl status sshd 

systemctl status httpd, mysqld, etc. 

8. Reboot (Last Resort) 

If system is frozen and console access is available, consider a reboot: 

Use reboot command to reboot the VM. 

Additional Notes 

If the issue is due to a host key mismatch: 

Run: ssh-keygen -R <hostname> then retry SSH.