Asus vh232h out of range, Mac mini thunderbolt to vga

Hey guys,

Pretty much what the title says.....

Mac mini

Asus vh232h (VGA only, no dvi socket)

Thunderbolt to VGA adapter

VGA cable (I've tried several)

(Benq monitor running fine on the hdmi port)

In short, if I use a VGA cable under 1.8m, there's no problem.

If I use a cable of 3m in length, or two x 1.8m cables, I get a "Out of range" message on the monitor.

(My office is shared space, so I need the Mac mini to be inside a lockable cupboard. That means I need a cable longer than 1.8m)

FYI, I don't seem to be able to set the asus monitor resolution in Mac settings (not sure if it can be done when monitor is 'out of range', but I can see the Asus in Display settings, Arrangement. It looks about half the width and height of the benq.

Is a monitor supposed to connect successfully over a 3 m cable?

Will a thunderbolt to dvi adapter work? (Would have to buy new monitor)

Any other ideas?

Thanks,

Darren