External display not recognized after clicking red text

nulz wrote:

I will have to bring my laptop away from my university for those tests; everything I have been testing has been on teaching lectern with iMacs or faculty laptops; hooked up to different projectors via HDMI or USB-C; Thus, this has been problem for people giving presentations; my clients don't do AirPlay on campus wi-fi. 

If the projector is directly attached, there should NOT even be a "Stop Extending" button. This is meant for Airplay devices only.

The only thing I can advise in this instance is to just unplug the HDMI cable when you're done.

That is what is supposed to happen, anyway. Your mac is supposed to detect directly attached displays and adjust automatically when they are disconnected.

Connecting via USB-C or HDMI should not use Airplay at all, but you seem to be seeing something that I too have seen in one or two occasions: even though the project is directly attached, the Mac behaves as if it were using Airplay. That, in my mind, is a bug.

I am running my Mac with an HDMI display, and every day when teaching with HDMI or VGA projectors.

Here is what I see: NO "stop extending" because the display is directly attached. To stop just disconnect the display.

Now here is what I see when my Apple TV is being used as extended display. Note that my HDMI attached display never even shows here, even though it is still in use (but of course shows in System Settings->Displays).

I can click on "Stop Extending" and then extend again without issue.

Bottom line is yes, this is a bug: directly connected displays are sometimes treated as if they were Airplay devices.

Sorry, I cannot reproduce your bug on macOS 26.1. I select my other Mac in Screen Mirroring and choose Extend Display. I click the red Stop Extending button and the other Mac returns to its normal desktop. I then go back to the Screen Mirroring control and the Mac is available, I can select it and it starts as Extended. Rinse and repeat, it's fine. Same with my iPad and one of my Apple TVs that I tried.

So, I think there's something else going on with your Mac. Or with the AirPlay functionality on your 3rd party device (as above, I'm using all Apple products, though not all of them are on xOS 26).

nulz wrote:

I will have to bring my laptop away from my university for the AirPlay tests; everything I have been testing has been on teaching lectern with iMacs or faculty laptops; hooked up to different projectors via HDMI or USB-C; Thus, this has been problem for people giving presentations; my clients don't do AirPlay on campus wi-fi; but I will test it.

If you are connecting via a cable, then you're not using Screen Mirroring. If you are seeing the projector in the Screen Mirroring controls, then it's using AirPlay. The screenshot in your initial post shows the Screen Mirroring controls, and that means you are using AirPlay whether you know it or not.

Stream video and audio with AirPlay - Apple Support

Here are two screenshots of my menu bar when I have an external display connected via HDMI and my iPad connected via AirPlay/Screen Mirroring. I'm running Sequoia on this Mac, but you indicated you see the issue there, as well. Note that there are two similar-looking, display related icons in the menu bar. For the first, I clicked the Displays icon and for the second, I clicked the Screen Mirroring icon that is in your screenshot. Notice that the display connected via HDMI (an Asus VN279 monitor) shows up in the Display controls (as does the AirPlay connected iPad) but the monitor does not show up in the Screen Mirroring controls.

First thing I'd try is to see if it occurs within the ecosystem, e.g., try Screen Mirroring (extended) from one Mac to another Mac.

Odd, I do not see that. For me, a wired connection shows up in Displays but not in Screen Mirroring. AirPlay is wireless only. As previously shown for Tahoe, also in Sequoia when I do use AirPlay / Screen Mirroring and click the Stop Extending button, the previously shared display remains available.

Sorry, not sure what else to suggest. Seems that something is different about your setup.

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