Website 1 out of 5 times, doesnt load or loads in an incomplete way (520 error)

Hello,
all ou tof sudden these last days, our website, 1 out of 5 times, doesnt load or loads in an incomplete way.
By doing an inspect, I see some 520 errors.
Can someone provide some help here? Unfortunately I am not very familiar with these kind of issues so please try to explain as clear as possible.

PS. I have put cloudflare to development mode, but this didnt help.
Also I have added cloudflare ips in the server firewall allow list, but this didnt help, too.

Thanks in advance for any help.

Hello,

Sorry to hear you are having issues with 520 errors. These errors indicate that the origin(web server) sent back a response that was not expected. Now this can be that the origin closed the connection prematurely or that it is resetting the connection being made. Below is article that details the common issues that can cause this.

When you are able to reproduce the issue carry that time stamp and check the origin(web server) to see if you can view the errors that are aligned with that 520. It will then help you remedy this. I would work with your hosting provider on this to get to the root of the issue.