Quote:
Originally Posted by zackhatfield
I'm using a Dell WD19S docking station, brand new, and am having all the same issues. The dual external Dell U2415 monitors will only mirror one another. SuPeR fRuStRaTiNg  |
To the best of my knowledge, the Dell WD19S docking station does NOT use DisplayLink technology. My theory is supported by the fact that Dell does NOT provide a DisplayLink driver for download from the product's support page -->
https://www.dell.com/support/home/en...w-dock/drivers
The dock most likely has a DisplayPort MST hub which enables multiple displays, and DisplayPort MST technology is NOT supported in macOS. This is why both of your displays are being mirrored.