How to run multiple servers?

I have mineOS set up on my old gaming laptop which is now the dedicated server. I have one server set up with a world to play with certain friends, and I want to set up a second which will be used with a different group of friends. Basically, I will be only running one at a time and I just want to know how to set up a second one and how to add it to minecraft separately from the first. I assume it has to do with using a different port number, so for example if I use port 25566 instead, I guess that SHOULD be important. The problem I see that I don’t know how to solve (and I may be missing something entirely…) is that when I put in the address on minecraft when adding the server, I put in simply the external IP address right? But its the same address as the first server… So I am not sure how to set up the second one… Sorry if I over explain… Thanks for any help!

Firewalls are in place for non-standard ports (25565 is the standard Minecraft port)

Use the following wikipage to hep you open up additional ports for any number of servers: iptables firewall

Thanks for the quick reply! that looks very helpful. The other part of the question is how would I go about adding it to minecraft? when I input the external IP should I add :[portnumber] to the end? and also I was using noip duc and it is set to use just the external IP of the server, how can I differentiate the two servers as separate on the minecraft client itself? Thanks and sorry if this is a bit of a silly question

Portnumbers are pretty much always important, all the time. The convenient thing is that when a port number is the default, it can be left out–and the app itself adds it for the user.

So when you type in “” in your browser, the browser uses (but doesn’t print) the “”. Likewise with minecraft. When you type in (made up obviously) in Minecraft, Minecraft auto-appends to it For 25566, you just have to tell it deliberately. Typing in the :25565 is okay all the time, just not necessary.

This is also how Minecraft would know the difference between the two servers, via the difference in port values.