Use an iMac with Thunderbolt as an external display I can't manage to connect my iMac (Retina 5K, 27-inch, 2017) Display with my  MacBook Pro (15-inch, 2018).

I have an Apple Thunderbolt 3 USB-C cable, both computer are on (logged with an admin user), but nothing happen when I press Cmd-F2.

I tried to use AppleScript in case something was wrong with my keyboard, but same issue.

tell application "System Events"
    key code 122 using command down # Cmd-F2
end tell


Tried the other way round (from my MacBook Pro) same thing...

FY, I don't think this is an issue but both computer are in a different VLAN

iMac : 10.15.4 (19E287), MacBook Pro 10.15.5 Beta (19F72f) (pretty sure had the same issue when both was in 10.15.4)
I should had read the KBase better .... Use your iMac as a display


  Note: Target Display Mode isn’t supported on iMac models with Retina
  display. Only iMac (27-inch, Late 2009), iMac (27-inch, Mid 2010), and
  iMac (Mid 2011 to Mid 2014) support Target Display Mode.