mac mini 2018 will not send to monitor

What Adapters and Adapter cables have you tested?

Sadly those old VGA/DVI monitors can be a little tricky with the newer Mac Mini's.

Keep in mind that not all aftermarket USB-C to DVI or USB-C to DVI adapters are created equal.

For help choosing a compatable USB-C to DVI adapter, see > https://top10best.how/usb-c-to-dvi-adapter?

The other option, is to just replace the older VGA/DVI monitor(s) with modern HDMI and/or USB-C display(s).

FWIW I used to have two old Samsung VGA/DVI monitors connected to my 2018 Mac Mini.

For the first DVI monitor I used an old Mac Mini's Apple HDMI to DVI adapter in the HDMI port.

For the second DVI monitor I used an old Mac Mini's Apple HDMI to DVI adapter and a USB-C to HDMI adapter.

Luckily, I had saved several of the old apple hdmi to dvi adapters from earlier Mac Mini's and they work.

I agree and think that you will be much happier looking at a newer display.

What display?

(make & model)

Check out the following Apple support article,

at > Connect a display to Mac mini - Apple Support