Here are the steps on how I got it to work
I'm running Pi-Hole on a Ubunu bare and AdGuardhome on a RPi Zero. I generated a cert. from LE with my domain for the AGH. With v6.0 I decided to use the same cert. by copy the 2 pem files (fullchain and privkey) to Ubuntu running Pi-Hole v6.0. After copying the files, combine them into a single PEM file (server.pem), then move it to /etc/pihole
- Edit the Pi-hole configuration to use the new SSL certificate - sudo nano /etc/pihole/pihole.toml
- Changed - domain = "yourdomain.net" and cert = "/etc/pihole/server.pem"
- Restart Pi-Hole
I can securely access both AGH (443) and Pi-Hole (8443) using the same domain name using diff. port