Website down after restore on new server

I have a basic WordPress site running on Hestia that was installed on Ubuntu 20.04 VM and was stable for long time.

It uses Cloudflare for SSL, I followed this video actually (it’s how I first found Hestia!).

Stupidly I ran do-release-upgrade on this server to upgrade to Ubuntu 22.04. While the update completed, the Hestia control panel was no longer available.

“No matter” I thought. I destroyed the server, installed Hestia on a fresh Ubuntu 22.04 and restored a backup of my web user from the day before.

After restore, the site started responding with 502 Bad Gateway (screenshot).

What’s interesting, is if I re-save the Cloudflare Origin Server SSL certificate and key on the “Edit Web” form, the website becomes accessible. But eventually after a few hours it goes down again.

I have revoked and replaced the certificate, but this doesn’t seem to solve the issue. Any ideas?

That seems to be a cloudflare error. You could try turning off proxying (orange cloud → grey cloud) and see what happens.

My first guess is that maybe you have Cloudflare’s SSL mode set too strict?