You need to either use your
IPV4 address. = Does not require opening ports = Local Server
Global IP Address = Requires Opening Ports = Online Server
To find your IPV4 open CMD= Command Prompt Type ipconfig and look for IPV4 Address and use that IP in ur client/server
To find your global IP go to
What's My IP Address? - Obsolete Browser Page and then use that in your client/server but you got to be able to portforward which will require you to go into your router and open up ports.
And yes all PC/Modems have IPV4 Address. If not you would have no internet.
GL,