Create Wi-Fi access point in macOS without Internet connection I want to use Keynote.app on my iPhone to operate a Keynote presentation on my MacBook Pro. In order to do that, both iPhone and Mac needs to be on the same Wi-Fi network. But sometimes, there is no Wi-Fi available or it is really unreliable.

I used to solve this by creating Wi-Fi access point on my MacBook. But with macOS High Sierra, it looks, that you cannot create proper Wi-Fi access point without tethering Internet connection. Because, in case I am not connected to ethernet, after creating the Wi-Fi access point in MacBook, I can see it on my iPhone in the list of available Wi-Fi networks, but it says, it has no Internet connection. So even if I try to connect to it, it shows this little tick icon next to the name of the wi-fi, but there is no Wi-Fi icon in the iPhone status bar. And it acts like it is not connected to the Wi-Fi as I am not able to manipulate the presentation through the Keynote app.

The same counts if I want to control some game with my iPhone (like Real Racing 2, which needs both iPhone and Mac to be on the same Wi-Fi network).

Is there any chance to creating a Wi-Fi access point on MacBook that is not otherwise connected to the Internet? I have tried searching for a solution on StackExchange and on the Web but to no avail.
This sounds like your iPhone deciding not to use the Wifi network it is connected to - perhaps it is instead directing all traffic to the Cellular data connection, since that does have internet access.

Perhaps try Disabling Cellular Data in addition to what you've already done above, so the iPhone has only one available network to send data to.