macOS 11.0 Big Sur or later: For older versions the workflow might be a little different. To use your mac as a hotspot it has to has a working wired internet connection via RJ45, Thunderbolt or USB.
1. Open Settings > Sharing
2. Set the sharing options.
Select Internet Sharing on the left. Choose your Ethernet connction as the connection to be shared. Choose WiFi as the method to share the Ethernet Connection. Now open the WiFi options.
3. Set Wi-Fi options.
You can set the name of the network to whatever you want. Out of the box it’s set to your mac’s name. You should leave the channel set to 1. You can choose the password to whatever you want, but you have to remember it as it’s the password your devices need to connect to your mac-hotspot.
4. Confirm the warning. We as administrators give you the permisson to do so.
5. Done! Now your hotspot is active. You can recognize this by the green dot and status in the menubar.