Mac mini (2018) supports one HDMI display with a resolution of 4096 x 2160 at 60Hz, plus one of the following configurations:
- One 5K display with a resolution of 5120 x 2880 at 60Hz
- Two single-stream transport (SST) 4K displays with resolutions of 4096 x 2304 at 60Hz
- One multi-stream transport (MST) 4K display with a maximum resolution of 4096 x 2304 at 60Hz
Connect to Thunderbolt 3 ports on different buses
If you connect displays to the Thunderbolt 3 ports on your Mac mini, use different Thunderbolt buses when possible. Don't connect more than two displays to any bus. If you connect a 5K or MST 4K display, you need to use a different bus for each of these displays.