I am using this monitor in portrait mode as a second monitor for both a MacBook Pro (Late 2016 - A1707) and a Windows PC. I had to remount the monitor upside down in order to spin it to mimic 270 degrees as it only spins 90 (I wanted the controls on the right hand side once portrait - took moments and only four screws required on the Vesa mounting). I am using DisplayPort (to USB-C, using this cable - https://www.amazon.co.uk/gp/product/B01EXKDRAC) from the MBP and HDMI from the PC. As the monitor is natively 75Hz and the MBP is 60Hz (as another reviewer already pointed out), connecting them knocked the text a little larger on the MBP. I simply needed to tweak the MBP display properties, set Resolution to 'Scaled' and Text Size to 'More Space' and the MBP all looks back to how it was.