macOS Catalina - problems detecting external monitors

I am using MacBook Pro 15-inch, 2018 with Catalina 10.15.4.

I am trying to connect 2 external monitors (Samsung S24C450) via USB-C -> DVI converter. Both monitors are then connected via DVI interface.

From both monitors only one is detected (one of two randomly) or none of them works. Disconnecting usb-c converter from laptop, DVI cable from converter or DVI cable from the screen - doesn't help. Disconnecting screens from power source, does not help either, nor restarting laptop.

This seems to work completely randomly. How do I force Mac to re-detect screens and use both of them, not only one?

Solution 1:

How exactly are you connecting your monitors to your MacBook Pro, and what else do you have connected to it?

The MacBookPro's with 4 Thunderbolt 3/USB-C connectors actually have 2 Thunderbolt 3/USB-C buses, each connected to 2 ports, one pair on the left side of the computer and one pair on the right side. The specs that say the Mac can support 2 or 4 monitors do not mention this, but the fact is the Mac can only support half that number on each side. 2 * 0.5 = 1 so the spec is not lying, but sometimes you have to pay attention to which side of the Mac things are plugged into.

Still, the Mac should support 2 DVI-resolution DisplayPort over USB-C monitors per bus, which makes me wonder exactly how you are connecting the monitors.

Try connecting one monitor on the right side of the computer and the other monitor on the left. Alternately, try connecting them both on the same side of the computer, connected directly to the computer and nothing else connected to that side.