iMac in sleep mode not available

Hi, I am an unexperienced user and it is the first time I have installed openHAB on my iMac. I also have installed the openHAB cloud service for Remote access using the openHAB app on my iPhone. This works fine until my iMac returns to sleep mode, then the network connections are closed and so the iMac is not available anymore for the app. Anybody knows how to solve this problem?

Check your power settings to make it not go to sleep. A Google search should provide plenty of tutorials.

I know but I do not want the server to be awake al the time. Isn’t it possible to wake up the server when the iPhone app is active or openHAB wants to report a status change of a device like a door sensor?

No, either the machine is up and running or it is asleep and no programs are running. That is what sleep mode means. Nothing is running.