Installing certbot

sudo apt-get install software-properties-common
sudo add-apt-repository universe
sudo add-apt-repository ppa:certbot/certbot
sudo apt-get update
sudo apt-get install certbot

Issuing a certificate

Now, let’s run certbot to issue a certificate for our server:

sudo certbot certonly

Select 1: Spin up a temporary webserver (standalone) and press enter.

Follow the instructions on your screen until it asks for your domain name

Once the certificate has been created by certbot, we need to convert it to PKCS#12 format, since it is required by Plex Media Server.

sudo openssl pkcs12 -export -out /var/lib/plexmediaserver/certificate.pfx \
-inkey /etc/letsencrypt/live/<server's domain>/privkey.pem \
-in /etc/letsencrypt/live/<server's domain>/cert.pem \
-certfile /etc/letsencrypt/live/<server's domain>/chain.pem

it will ask for a password twice, which will be used in Plex settings.

Our certificate is located in /var/lib/plexmediaserver/certificate.pfx and we need to change the ownership to plex user:

sudo chown plex:plex /var/lib/plexmediaserver/certificate.pfx

Plex Media Server settings

Navigate to http://<server’s domain>:32400/ and see the following screenshot.

Navigate to Settings > Network and fill the appropriate fields as shown above. Save when finished.

I had to restart the plexmediaserver service for the changes to take effect.

sudo service plexmediaserver restart

Now, if you navigate to https://<server’s domain>:32400/ you’ll see the green padlock.

Steps taken from srilankanchurro GH