The zfold 3 dex is not compatible with devices that work with s21 ultra. I use to use my s21 ultra with dell laptop docks for Dex, but the zfold 3 doesn't seem to detect the screen out on these where as the s21 ultra would output to anything. Dex works fine wired directly but nothing on any dock I've tried, keyboard , mouse and power all work though. Not sure why Dex output has been changed or if it's a bug but needs to fixed as it limits device use.