Unable to SSH onto GCE VM after reboot

Please find below some general recommendation to troubleshoot this issue.

• Make sure the VM boot disk is not full and has enough memory space after system updates. You can opt to resize VM disk and detailed steps are here.
• Make sure from VM serial console output that the instance has fully booted up.
• Once the instance is booted confirm if ssh daemon is running. Serial console output will have information about ssh daemon. If ssh service is not running you can use interactive serial console to start the service.
• Make sure you have firewall rule configured in GCE network to allow ssh port.
• Make sure firewall on the instance(e.g. iptables) is allowing the ssh port. You can use interactive serial console to disable firewall on the VM, if required.
• You can try ssh from cloud console terminal. You can find more details here. Moreover you can try ssh in verbose or debugging mode: #ssh -v username@host_ipaddress