How to Generate several Dedicated Server?

i’ve seen many of games using kinds of channeling system or something.

I Mean
There are several room or map and People can enter the room and play, chat etc.

So
I want to try this system in ue4 with dedicated Server.

We know One packaging One Dedicated Server like when you launch dedicated server with projectnameServer.exe -log

So If i want to make several Map, I have to launch several Dedicated server.

But the Rule of One Packaging One Dedicated Server disturb me.

So How to Generate several Dedicated Server?

In Ue4 editor > project settings > Server Default map
is only activated through the port:7777.

I want to other maps with port:7778 ~ 777x

Any Advises?