How do i make my windows server 2012 connection private?

After a restart of one of our servers (a windows server 2012 r2), all private connections become public and vice versa (this user had the same problem). Stuff like pinging and iscsi stopped working, and after some investigation it turned out this was the cause.

The problem is that i don't know how to make them private again Left-clicking the network icon in the tray shows the "modern" sidebar, but it only shows a list of connections, and right-clicking them doesn't show any options.

Where can i find the problem and how to change it? I have to make one of the connections public (internet access), and two of them private (backbone).

Powershell. Here is an example of changing the network profile of a network interface called Ethernet1 from whatever it is now to "Private." I got this info from Get-Help Set-NetConnectionProfile -Full .

PS C:\>$Profile = Get-NetConnectionProfile -InterfaceAlias Ethernet1

PS C:\>$Profile.NetworkCategory = "Private"

PS C:\>Set-NetConnectionProfile -InputObject $Profile

Documentation: https://technet.microsoft.com/en-us/library/jj899566(v=wps.630).aspx