What error message or number are you receiving?: 525
See the other thread I referenced for more info. It is closed so I cannot reply there…
Everything was working for the last weeks until I suddenly got the error with any interaction from my side.
It looks like the certificate on your origin server may have been removed. To identify the cause and resolve the issue, please start out by pausing Cloudflare. This will enable you to connect directly to the origin and see the exact error message. Then you can resolve the issue and enable Cloudflare once again.
Thank you but I verified the SSL certificates are there on my VPS. I have multiple Dokku apps and they all have the certificates, I even reran the command to add one.
I now disabled proxying to verify like you suggested. I have to wait a bit to see.
The SSL connection is failing due to a bad signature on the leaf certificate. I am not sure what might be the cause of this, and troubleshooting SSL issues unrelated to Cloudflare is outside the scope of this forum.
You might benefit from generating and installing a Cloudflare Origin CA certificate. These are only valid for connections between Cloudflare and your origin, but the certificates can be set to last up to 15 years so you don’t have to deal with renewal.
If an Origin CA certificate does not solve the issue that could indicate the issue is with your web server configuration.