This guide, gives a step-by-step to installing Teamspeak 3 (3.12.1) 64 bit server on Ubuntu 18.04 and 20.04

Step 1:
Login to SSH as root

Step 2:
Run the below commands:
Note: During the apt-get upgrade command, you maybe asked about the grub load. Press Enter

apt-get update
apt-get upgrade
apt-get dist-upgrade

Step 3:
Let create a user for the Teamspeak 3 server.

adduser --disabled-login teamspeak

You will be asked for user information for teamspeak. Press Enter for all the questions.
You will also be asked is the information correct. Press Enter.

Step 4:
Type the following command

cd /home/teamspeak/;su teamspeak

Step 5:
Run the following commands to:
Download Teamspeak, extract it and tidy up.

wget https://files.teamspeak-services.com/releases/server/3.12.1/teamspeak3-server_linux_amd64-3.12.1.tar.bz2
tar xvfj teamspeak3-server_linux_amd64-3.12.1.tar.bz2
cd teamspeak3-server_linux_amd64
cp * -R /home/teamspeak
cd ..
rm -r teamspeak3-server_linux_amd64
rm teamspeak3-server_linux_amd64-3.12.1.tar.bz2
touch .ts3server_license_accepted

Step 6:
Now we start the TS3 server

./ts3server_startscript.sh start

Make sure you copy and save the security token and Server Query Admin Account details, once the server has started.

Step 6.1:
Press Enter. This will return to the command prompt.

Step 7:
Now we need to stop the server and return to root, enter the below:

./ts3server_startscript.sh stop
exit

Step 8:
Now we will create a restart script using systemd to restart it on boot.

Run the below command (This should open a blank pape)

nano /lib/systemd/system/ts3server.service

Step 8.1.
Copy the below and paste it:

[Unit]
Description=Teamspeak Service
Wants=network.target

[Service]
WorkingDirectory=/home/teamspeak
User=teamspeak
ExecStart=/home/teamspeak/ts3server_minimal_runscript.sh
ExecStop=/home/teamspeak/ts3server_startscript.sh stop
ExecReload=/home/teamspeak/ts3server_startscript.sh restart
Restart=always
RestartSec=15

[Install]
WantedBy=multi-user.target

Step 8.2:
Now we need to save it

Press CTRL and X together, then Press Y

Step 9:
Now we need to enable it, by typing in the following command

systemctl enable ts3server.service

Step 9.1:
Type in the following to restart the server)

reboot

Step 10:
Reconnect to SSH, once the server has restarted and enter the following command:

systemctl status ts3server

Step 10.1:
This should return an ouput look for:

Active: active (running)

Step 10.2:
To return to the command prompt, you will need to:
Press Q