External monitors not detected on Ubuntu?

Question

linux

(
Further Ubuntu version is 18.04.3
Kernel: x86_64 Linux 5.3.0-26-generic
GPU: GeForce GTX 1660 Ti
Nvidia driver 435 (proprietary).
)

I bought myself a Legion Y740 laptop. Initially I installed it on Ubuntu, and the connection to external monitors worked for me (at least through thynderbolt, the image was displayed, Hdmi did not check at that time).
Then I decided to install a dual block from windows10 and ubuntu.

But after all this, after a new installation of Ubuntu next to Windows, the system stopped detecting external monitors from the word at all.
(Windows sees everything properly. So the options to change cables, check video slots or eliminate the use of adapters immediately disappear).
I tried different versions of proprietary and open source nvidia drivers (changed them via Software & update in the Advanced tab of the diver).
I also tried the default Nouveau driver for X, but the result is the same.

I was more confused by the output:

xrandr
Screen 0: minimum 8 x 8, current 1920 x 1080, maximum 32767 x 32767
eDP-1-1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 344mm x 193mm
   1920x1080    144.00*+

in theory, there should be information about at least (thynderbold, Mini-DP, hdmi ports).

There is an option in the BIOS - Adaptive option (the choice is either discrete or adaptive option).
I tried to turn it on - only discrete graphics, but in this case, even on the laptop screen, an image was displayed in resolution (obviously less than 800x600. Maybe somewhere in 400 units in width). (In addition, the resolution in Grub also dropped to the same values. Windows works fine).

I tried to set the settings through Nvidia - only nvidia, or only intel graphics - the result is the same.

Tell me, in which direction to dig?

Answer 1

What was the source of the problem was never found.
Either the config created for the newer version of the driver was not correct for working with multiple monitors, or it got crooked.
This can be confirmed by the fact that after reinstalling the system from scratch, the 435 test driver did not detect monitors, while after switching to the stable 430 driver, everything started up as it should.