Hum,
I guess the docker engine provided by QNAP is not able to mount files, but only directories.
Can you keep your certs folder and rename cert.pem to certificate.crt and key.pem to certificate.key ?
If you mount your certs folder inside /etc/ssl/certs/ folder of the container, you will have problems as this path contains other mandatory certificates.
Can you edit next your docker-compose.yml file:
Use the non-root image instead of the root one: passbolt/passbolt:latest-ce => passbolt/passbolt:latest-ce-non-root
Update the volumes definition:
volumes:
- gpg_volume:/etc/passbolt/gpg
- jwt_volume:/etc/passbolt/jwt
- ./certs:/etc/passbolt/certs
Finally update the ports:
ports:
- 8080:8080
- 4433:4433
Let me know if it fixes your issue.
Best regards,