How to set up second screen in iMac 2017 with macOS 10.12.6 Sierra?
I solved the problem finally, today I bought cheap Lenovo adapter and it works well. Previously unfair ad drove me to make the wrong decision to buy incompatible adapter. My brand new EZQuest cable working well with old MacBook 12" 2015 refuses to work with iMac 21.5" 4K 2017.