External monitor for a MacBookAir M1
Putting this out there, in case someone was puzzled by the same issue.
Got a MacBook Air M1 a few days ago (definitely feels fast). Intended to plug it into my big monitor here at home, but neither the Mac nor monitor would recognize each other -- the monitor would claim "no signal"on the port it was plugged into. The monitor is less than a year old and has a proven track record handing a mac Mini on the HDMI port and an MacBook Pro 2011 on the DisplayPort.
I pondered the culprit. Was it the Air M1, the monitor, the USB-C hub or the cable? Fortunately I had some options.
Long process short, I tried different cables, different USB-C adapters, and a couple different monitors, and the conclusion I reached that the Air M1 would ONLY sync with any monitor with USB-C to DVI connection.
Last night I updated to Big Sur 11.1 and magically the problem was solved! All the combinations I had tried before now worked. Every cable, every adapter all showed the Air M1 on the "big screen". So, it was an macOS bug.