Display

The display is an ACER S271HL connected with an HDMI cable. It is an intermittant fault and has occured 2/3 times. I haven't tried disconnecting and reconnecting nor powering off and on. No I haven't tried sleeping instead of shutting down. Initially the mini would power up in 5 seconds and display switching on was instant and showed a loading bar schematic but now the monitor turns on when the mac is switched on then "no signal" is displayed it powers off and then in about 20secs powers on again. I plan to replace the HDMI cable and try the mac with other displays and eliminate the possibility of a monitor or cable problem.

I have tried sleeping the mac mini it went to sleep instantly and woke up instanly with no delay. I have tried powering off display it boots but after 10s or so shows display again. I'm a bit wary about disconnecting display HDMI cable while its powered up. The thing is its settled into an acceptable working mode it just seems to take a long time for the display to appear. I tried it on a TV with HDMI and it still takes 20secs or so to appear. It's just dented my confidence in the device. I've also had momentary lapses in blutooth connectivity with the magic keyboard and sometimes pink pixilations appeared on start up screen. It's brilliantly fast when it's working just hoping these unsettling glitches don't continue.

Thanks I'll try these options. USB-C to HDMI and premium HDMI cable.

I did try these suggestions a premium cable and a USB-C to HDMI. The first had no effect and the latter seemed to make the monitor start up time even longer.