I have an S20 phone and S6 tablet and have been using DeX on both devices on a variety of screens. Yesterday DeX was playing up on the S20 and today I can't get it to work at all. The different screens / cables all work fine with the tablet but not the phone. I can connect the phone using a usb-c to hdmi connector, but this is missing a few features.
Could this be a software issue, or is the usb-c port on the phone the issue? If it's the port, do Samsung fix these under warranty - it's less than a year old.