So I took my M4 Mac mini to the Apple User Group meeting only to be almost stymied by old technology. I could not connect it to either the venue's big wall-mounted smart TV or to an Apple TV 3rd gen that was visible on the TV itself.
I tried demonstrating my Soundcore Boom 2 Plus high power Bluetooth speaker but it was not visible in Bluetooth settings even though it had worked at home.
The venue's TV is not new and offers a maximum resolution of 1920 x 1080. i had practised at home on two different HD TVs using different HDMI combinations, all of which worked fine. Those were 4k-capable HDMI cable, 2k cable, USB-C to HDMI and a USB-to-HDMI adapter using either of the two available HDMI cables.
Eventually we got the wifi streaming connection to the TV working but these things were no issue in previous months when using the M3 MacBook Air.
The Boom 2 Plus could connect to the iPhone so I was able to demonstrate the room-filling audio capability of the device via the iPhone Mirroring app. So damned frustrating.