I was running a s8 and would mirror the screen to a non smart TV via USB to hdmi cable. I would just plug in the cable and select the correct channel on the TV and it worked.
On my new s20 plus, I plug in the same cable and dex opens by default. Turning off dex in the s20 hdmi setting results in a black screen and only audio being sent to tv.
No option to switch to screen mirroring is available.
I spoke with Samsung support they said I need to use a smart tv and connect via WiFi. But there are videos on line showing a simple USB to hdmi cable for mirroring.
Any ideas? Thanks