Don't edit files. Read all of these steps.
create a self signed cert in the omv web interface.
set that cert for the omv web interface
sudo omv-showkey sslcertificate
get the uuid for the cert you created
Then run my script https://github.com/ryecoaaron/scripts/blob/main/update_cert.sh
update_cert.sh b11bfa4e-11dc-4e49-a450-9fee0d786702 cert.pem privkey.pem letsencrypt
You can set this same command as a hook script to run every time the script is renewed and the web interface will use your cert. I use this will all of my omv systems except I am using acme.sh to get a wildcard cert.