Just yesterday I couldn't connect my laptop to a new classroom projector with a USB-C input. When I selected "Duplicate Display" it caused my whole system to hang unresponsive. Works fine in other rooms with HDMI to USB-C. I have no idea what is wrong.

My new iPhone XS doesn't connect to my car's bluetooth, while the 4 year old phone I replaced does. My wife's iPhone 8 does. I'm stuck using an audio cable like it's 2003 again.

That reminds me of a situation at work.

A new coworker couldn't connect to the internet when he had a an Apple Thunderbolt display connected to his ~2014-2015 MB Pro via thunderbolt. Mystifying. Even more mystifying was corporate IT going "oh yeah just don't use it".

That's probably because he had his network connection priorities ordered so that the TB networking had priority and there wasn't a valid route on the connected network to the TB display. That's very likely a fixable problem, as I have encountered similar and resolved it.