A reboot will often fix this problem. Try rebooting your server. 521 means the server didn’t respond when cloudflare tried to connect. If it resolve the problem. Please update post with logs and further information about your server such as OS, what your running etc

Hey @gtrclub2019

The logs you have shared indicate read-only filesystem on your droplet which would have caused issues. In such cases, you should mount recovery iso, reboot and then run a file system check. Once done remove the recovery ISO and reboot again. Please let us know if it helps. Otherwise, let us know the output of /etc/fstab along with the applications running on your Droplet.

Let me know if you have any further questions.

Regards,
Prakash Jha
Developer Support