You can test the certificate with this website: SSL Test. If the following error occurs, the certificate must be adapted:

3. How can I customize the certificate?
The so-called "intermediate certificate" must be integrated into the COYO certificate:
- Log into your COYO host as user coyo and navigate to cd /home/coyo/
- We assume your certificate is named "cert.pem" (defined in your .env file) and you saved the intermediate certificate as "inter.cert" therefore please us: cat inter.cert >> cert.pem sudo ./stop.sh sudo ./start.sh