Problem with Google Assistant integration (Could not reach...)

Hello everyone.
My first post here, so I want to greeting all the community.

I trying to setup a HA with Google Assistant but without success.
I used a this instruction (in Polish) but it’s very similar to the one from HA page.

Previously I have it setup successfully (according to this instruction) with HA in docker. I moved to the Home Assistant OS on VM, even setup the same machine IP as docker host had, move the all configuration from docker instance to HA OS but it wont work (even after account relinking from Google Home). So I tried setup everything from scratch but also without success.

What I’m facing is the message from bellow screen when I’m trying to add my HA project to Google Home:

I’ve seen before a topics in this forum about this message but in those cases people was able to see a HA login screen - I can’t. If I click [test] MyHomeAssistant then a white screen appear for a second and I see this error message.

My HA instance is accessible from Internet thru SSL reverse proxy (Apache2). I can do everything on this instance thru HA mobile app (thru Internet).

What I’m doing wrong. Is there any way to debug this (from HA or Google Cloud side)?

Best Regards,
Michał