deloptes composed on 2018-05-16 07:01 (UTC+0200):

> Felix Miata wrote:

>>> digitus 4K HDMI switch 4x1

>> What model is that switch?

> Felix, I wonder sometimes if you really read the posts. I said it
> is "digitus 4K HDMI switch 4x1" - you ask what model.

What you wrote looks like a description, not a model number. Model numbers are
generally required to ensure a item found is the item described, necessary to
ensure one does not make the mistake of choosing to acquire that exact same
badly behaving item.

>> 2-manually configure Xorg using xorg.conf to exclude possible modes except
>> 1920x1080. (Set PreferredMode, and set HorizSync and VertRefresh to narrow
>> ranges that can only compute to the 1920x1080 mode published in the manual
>> or provided by EDID when connected without the switch inline).

> IMO I need to set the physical size in xorg.conf, but your comment reminds
> me to check the EDID. I wonder if the monitor can talk to the PC at all

DisplaySize affects logical display density, not resolution/mode.

Talk to yes. Communicate, likely the problem. HDCP implementations incorporated
in HDMI are capable of causing all sorts of communication foibles which intended
or otherwise comprise obstacles to both violation of protection, and proper
operation.
-- 
"Wisdom is supreme; therefore get wisdom. Whatever else you
get, get wisdom." Proverbs 4:7 (New Living Translation)

 Team OS/2 ** Reg. Linux User #211409 ** a11y rocks!

Felix Miata  ***  http://fm.no-ip.com/