Product to be reserved for the short connections. Probably poor quality components.

This switch is probably fine for the short connectors (wire size less than 5m ... and again).
But a greater distance with guaranteed 4K quality cabling, can not get a signal without artefact or loss of quality.

However, after various tests, it appears that the artifacts disappear if the connection is reversed:

If the next connection is made: Source> cable 2m> Switch> 10m cable> Projectors: artifacts are present.
If the next connection is made: Source> cable 10m> Switch> Cable 2m> Projectors: artifacts disappear and quality 1080p @ 60fps is now possible.

This kind of result would seem to indicate that the HDMI output of the switch has weaknesses ... but it is unthinkable to wire a switch in this way (4 HDMI 4K 10m cables).

And as long as I am in the critical switch switch ... it was the third test, always with the same result on the wiring length.

Conclusion: avoid switches, unless you have an installation with a home theater receiver that handles much better video signals, it seems impossible to find a product like this that work properly.

This product is probably fine for small installation on a television, but absolutely not recommended for remote installations and / or projection. And even in the case of a small installation, I would tend to cast doubt on the quality of the signal transmitted in the end.