Cloudflare Error 523 means that Cloudflare could not able to reach your host web server. The common and general cause is that your DNS settings are not correct. Please contact your hosting provider to confirm your origin IP and after then make sure the correct IP is listed >your A record in your Cloudflare DNS Settings page.
If you owned website:
First of all Check your DNS Settings. 523 error means that Cloudflare could not able to reach your host web server. The common cause is- your DNS settings are incorrect. Simply go ahead and contact your webhosting service provider to confirm your origin IP and then make sure the corrector exact IP is listed for and your A record in your Cloudflare DNS Settings page.
Also read- 503 error- Service Unavailable: solution
504 error- Server is unavailable: solution
Internal Server Error :500 error
508 Error Resource Limit Is Reached- Details
Error 523 in Cloudflare
In Cloudflare Error 523 suggests that Cloudflare isn’t able to connect with the website host, or els in this case, your Linode. Here are 3 steps you can take to help resolve this:
First confirm that Cloudflare’s IP is pointing to your actual Linode’s IP.
Simply just Connect to your Linode and after then restart your webserver i.e-Apache2, Nginx.
Check for common problems on your Linode
Do you have enough disk space?
df -h
Is your key services active and listening?
netstat -plunt
Are you out of memory?
free -m
Is your firewall blocking connections?
iptables -S
