Re: Dell Support told me the Inspiron 3910's USB C port doesn't support video display - which sounded rather odd to me they are correct.  The desktop USB-C does not have Display port over USB function. Inspiron 3910 spec does not mention DP over USB-C.  all it says is  What happens if I plug my display into a USB Type-C port that does not support DisplayPort over USB Type-C? No video data will be received by the display, hence there will be no image on the screen.  How will I know if the USB Type-C connector on my device supports DisplayPort over USB Type-C? USB Type-C connectors that support the DisplayPort over USB Type-C will normally include the DisplayPort (DP) logo near the connector many modern laptops on the other hand have Display over USB-C built in their USB-C port. your latitude 5420 spec mentions 
Hi, I have  Monitor: Dell 27" 4K S2722QC PC: Inspiron 3910 i5 12th Gen with intel UHD 730 GPU I tried connecting the S2722QC monitor to the PC via the supplied USB-C cable, but the monitor reported no signal from the PC. I connected the monitor to my Dell work laptop (Latitude 5420 i7 11th Gen) and it worked fine (plus able to display 4K). Dell Support told me the Inspiron 3910's USB C port doesn't support video display - which sounded rather odd to me. I spent 45 mins on the phone with Dell and they checked all the drivers etc on the PC - no issues identified. Has anyone else come across this issue and is there a fix? Will a high speed HDMI 2.0 connection allow me to get 4K resolution? Thanks
Inspiron 3910 USB-C port not connecting to 4K monitor