I cannot use 4k on my 4k Screen? I'm out of ideas on what I can try to fix my problem. My configuration is as follows:


MBP2016 13" with two USB-C ports
a HooToo USB-C Hub (supports 4K)
a (brand new) HDMI Cable (also 4K/UHD compatible) 
a HP ENVY 27s monitor


I already know that 4K is only possible if my refresh rate will be 30Hz. I'm perfectly fine with that. But the option to change the refresh rate is 'grayed out' and I cannot find any options to change it in System Preferences > Displays.



(Text is in German - but I think you'll get the point)

Does anyone have ideas on what I could try?

NOTE: I've already tried the 'alt-click' trick on Scaled to see other resolutions.
Have you installed the HooToo shuttle firmware update for MacBooks? If not, you can download this directly from here.

I would download/install the firmware update first to see if that resolves your problem. This eliminates the possibility that it's a firmware issue with the HooToo hub (otherwise you could spend hours troubleshooting other causes for absolutely no benefit).

If you still have problems after installing the update, please comment below to let me know.