The Advanced Connections Settings dialog window is where you can modify the settings that tell Skype for Business how to connect to the Skype for Business servers.
Important: Normally you do not need change your Skype for Business sign-in settings. Don’t choose manual configuration unless your support team tells you to AND provides detailed guidance on the correct values to use.
Choose this to let Skype for Business Server automatically configure your connection settings.
Again, only choose this if you've been told to by your support team--and only if they're given you the server names you will need to supply.
Internal server name Type the FQDN (fully-qualified domain name) of your Skype for Business Server.
External server name Type the FQDN (fully-qualified domain name) of your Skype for Business Server or Edge Server.