Hello everyone,
after having a phone call and getting an email from acer support, I was able to update my thunderbolt 3:

Does "External GPUs supported: No" means, that I can not use the Asus MB169C+ External Monitor?
When I plug in the monitor, the orange lamp shows that there is energy income, but as soon as I push the power button, it says: DisplayPort No Signal.
Given the fact that I do not have the original Asus Typ C cable and just a cheap USB Typ C cable from Caletex might this be the reason for beeing not able to see anything?
Should I try it with a real Thunderbolt 3 (20 Gbps) / USB-C 3.1 Gen 2 Cable Or even ask Asus to re-send me the original cable?
Happy for getting any help.
Best regards.
[edited to comply with guidelines - removed links to protect user's Amazon account]