How to add support to an external monitor in Android? My Samsung Dex (with Android 7 in a Samsung Galaxy S8 phone) won't work with my LG 23MT75D-PU monitor. I think because the Android driver are not ready to talk with this monitor yet. I will want to know where i can fire a bug related with that fact or find a fix, by myself.

I really think this is an android question by nature. My Galaxy S8 have not a problem and also i considered, this is not a problem of Samsung Dex, but instead, this is a problem in the Android kernel, because it's where reside the modules to load the most commons drivers by default.
I finally found the problem. The Samsung Dex work only with an specific voltage, you can not connect it to any different power supply (like the usb ports of your computer). If I connect it to the power manager that come with the phone, it will be working well on my monitor.

Thanks all involved.