Wake the Mac whose screen you want to view and put both Macs on the same local network. On the Mac you want to reach, open System Settings → General → Sharing. Check that Screen Sharing is on and that the account you plan to use is allowed.
01Check the sharing setting on the Mac you want to reach
Section linkIn Sharing, click the info button next to Screen Sharing and review Allow access for. If it is set to Only these users, add just the account that needs access. macOS allows either Screen Sharing or Remote Management at a time. If a work or school Mac uses Remote Management, ask the administrator to check your access there.
02Make a fresh connection on the other Mac
Section linkOpen the Screen Sharing app and choose Network in the sidebar. Find the Mac and click Connect. If the Mac is missing from the list but you know its current hostname, use the new connection button and enter that hostname. If macOS asks you to sign in, use the name and password of an allowed user on the Mac you are trying to reach.
03Use the failure to narrow the search
Section linkIf the Mac is missing and a fresh connection also times out, check the network on both Macs in System Settings → Network and make sure the Mac you want to reach stays awake during the test. If a sign-in prompt appears but access is refused, recheck the allowed users and the account you entered. These checks apply to direct Mac-to-Mac connections on a local network.