Websites Showing "Web Server Down (521)" Error

Hello CyberPanel Community!

I’ve installed CyberPanel on Contabo Server Specs

8 Core CPU

I’m Using Cloudflare. I was testing with Bulk command of Cloning a website with option “Clone/Staging” i opened 10 tabs and submitted 10 subdomains for cloning like 1.webiste. com com com. but all of my other subdomains & domains are not working now. Showing Web Server Down Error 521.

Things I’ve tried to fix this

  1. Server Restarted
  2. Changed All type of settings in Cloudflare like SSL settings & Redirections
  3. Restarted All Services in “Service Status”
  4. Turned Off “Firewall” & Restarted etc.
  5. Deleted all the sites and data and installed sites again but still same error.

Nothing works for me yet.