If you're having trouble connecting to your Mac from a domain-joined PC, you may need to check your workgroup settings on your Mac.
On the Mac: open System Preferences and navigate to the Sharing section:
Choose your primary network adapter (the one that's connected to the same network as your PC) and select Advanced:
On the WINS tab, enter the name of the workgroup or domain that your PC is a part of. This is the most important step:
From your PC: connect to your Mac (e.g. Start, Run, \\Valid\Unc\Path\Or\IP\Address). You'll be prompted for a username and password. Notice that by default it wants to login with a domain account: