When you connect to a new network on Windows 10 you’ll have a panel come up on the right that looks like this.
Clicking yes sets it as a private network, clicking no sets it as a public and devices non-discoverable.
To edit these, open Reg Edit and navigate to
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\NetworkList\Profiles
To change between the two, find the network profile you wish to change, look at the “ProfileName” field. Then, find the “Category” DWORD entry and change the “Value data” from “0” – Public to “1“ – Private.