Log in to IONOS – you need three files:
- private key (
- certificate (
- intermediate certificate (
If you don’t have the private key, Revoke Old Certificate, then Reissue Certificate – on Firefox this is a bit weird but it’ll download the key file but until you open it won’t complete the reissue.
In Plesk go to Websites & Domains > SSL/TLS Certificates > Advanced Settings > Add SSL/TLS Certificate.
Enter a certificate name:
Scroll to “Upload the certificate files”:
Browse each file (it doesn’t matter that they’re
cer rather than
_INTERMEDIATE.cer for the CA certificate, then click Upload Certificate.