1

First Step

2

Second Step

Select your Server

3

Third Step

Make sure to Turn OFF the Server

4

Fourth Step

Under the General Section, Click the Files tab

5

Fifth Step

Click the server.properties file

6

Sixth Step

Scroll down to till you see max-players: [value] and edit the [value] to your prefered number and hit the Save Content button

7

Seventh Step

Now, Head to the Console tab and hit Start

There you go, You have changed the maximum capacity of players able to join your Server!
How to change Server SeedHow to change difficulty