[NAME]  The WD19 can only run dual QHD at the standard 60 Hz refresh rate when paired with a system that supports DisplayPort 1.4/HBR3 over USB-C.  The Latitude 7400 only supports DisplayPort 1.2/HBR2 over USB-C, and the lower bandwidth of that standard means you can only run dual displays up to WUXGA (1920x1200) or a single QHD display.  However, the Latitude 7400 was also available with Thunderbolt 3, in fact it may have been standard on that system.  If your system has it, you could get the WD19TB(S), which when paired with a DisplayPort 1.2/HBR2 system will tap into 4x more video bandwidth than the regular WD19(S), and therefore would run dual displays up to 4K 60 Hz or triple displays up to QHD each.  I wrote an explainer post on the various operating modes of USB-C and TB3, with particular focus on their ramifications for display setups, over here if you're curious.
Hi,I'm using Latitude 7400 and WD19 Dock, and I'm trying to connect two VHX-3276-QHD display, which is Maximum resolution is 2560x1440 through DP.when I connect, the one of the display is recognized properly, the maximum Resolution is 2560x1440,But the second Display's resolution is restricted as 1920x1080 and it's not selectable above this resolution in display settings. And this display, which has lower resolution is flickering and illegible almost couldn't recognize the characters. It seems depends to connect which display first, It's looks both displays seems have same problems. If I swap one of the DP cables connected to the WD19 to an HDMI cable, the maximum resolution will change to 2560x1080 for no reason.(Still can't use 2560x1440 Resolution.) But when I connect this HDMI cable to Latitude's HDMI Port Directly, (that means one of the DP cable is connecting to WD19, and one of the HDMI cable is connecting to Latitude Directly) these two displays show correctly. But I want to connect WD19 and not connect to Latitude, because I bring Latitude out frequently. Is there a way to achieve connect both display to WD19 correctly? I already tried to reinstall of Intel 620 Graphic driver, and updated WD19's driver, and Monitor itself's driver, and restarts and re-connection of display cables and WD19's Type-C USB Cable.
Maximum resolution of multi-display's second screen is restricted