I have a centos 7 vps and was going to install TeamSpeak 3 Server on it.

I installed it and have it running using ts3server_startscript.sh start

I did not configure anything within teamspeak.
i opened up some ports using the following:
sudo firewall-cmd --zone=dmz --add-port=9987/udp --permanent
sudo firewall-cmd --zone=dmz --add-port=30033/tcp --permanent
sudo firewall-cmd --zone=dmz --add-port=10011/tcp --permanent

Note: I have an application running on port 80 on the same machine. I don't know if that matters.

On first try i got
loginname="serveradmin", password="dummyPassword"
and token=dummyToken

I then open up my Teamspeak 3 client (windows)
Connections -> Connect
ServerAddress: The IP Address (I tried using port 30033 but the same result)
Nickname: serveradmin (same as in loginname)
Server Password: Tried empty or dummyPassword, or the password for the user that teamspeak is running on.
I however get "Failed to connect to server"

Am I missing anything?