I had joined a workgroup file server to a domain. However, when I went into the security tab of a folder that I wanted to grant an AD security group to there had been no option of selecting any user or group from AD. Only local security groups or users could be selected.
Simply, by rebooting and waiting this issue corrected itself. I’m uncertain as to why but felt the need to document it. Hopefully, this helps someone else that had the same issue.
Also, please note that some users may lose their connection to the server. If they don’t already have duplicate security groups and users in AD (with assigned permissions to those same folders…How would they? They haven’t been added yet!) you will need to ensure that they access the mapped drives and saved “network locations”. To do this ensure that they are still using the local user on the server by using the username structure “<servername>\<username> and then the password of the local user account that has the access. This will help ease any migration pains.
Essentially, you can authenticate against the local users or Active Directory.
I wanted to give this an update where you may run into an issue that I have run into. If you have a domain-joined PC connecting as the Local User if it has the same credentials it will work but when the server is joined there will be a connection issue and will have to delete and re-add the mapped drive to the user settings.