Hi @knightmare
check
to find a reason. May be the domain owner, may be a hacked server. May be a published private key.
That's a browser thing. If the browser doesn't allow an exception, replace the certificate with a self signed certificate.
Both things are independent. You can immediately create a new certificate.
PS: Checked your domain - https://check-your-website.server-daten.de/?q=1373.knightmare.ch
The domain isn't SDN listet - Specially Designated Nationals And Blocked Persons List (SDN) Human Readable Lists | Office of Foreign Assets Control - so that's not a reason.
And there is already a new certificate:
| Issuer | not before | not after | Domain names | LE-Duplicate | next LE |
|---|---|---|---|---|---|
| Let's Encrypt Authority X3 | 2019-09-02 | 2019-12-01 | 1373.knightmare.ch - 1 entries | duplicate nr. 1 | |
| Let's Encrypt Authority X3 | 2019-06-15 | 2019-09-13 | 1373.knightmare.ch - 1 entries |
But the old, revoked certificate is used.
So install the new certificate, don't create a new.