It's best to have all of your devices on the same HDMI version, which is HDMI 2.0, to avoid any issues with compatible formats. HDMI is backwards compatible but only to the in-common formats. An HDMI 1.4 sink receiving a signal from an HDMI 2.0 source can only utilize the HDMI 1.4 formats.
The best, and most reliable connection is a single connection, source to sink without any switches, adapters, wall outlets, etc in-between. You can use a switch in some cases but it's going to be trial and error. 4k HDR can be very unforgiving with its connectivity so you need to keep that in mind.
Cable distance can also be an issue. You're best off to use Premium High Speed HDMI cables for your connections. They are not a 100% guarantee that they will work but at least you know they have been certified by HDMI.org to meet all of the HDMI 2.0 hardware specifications. The cable is just a data pipe. It's the HDMI chipset version in the source and sink that ultimately decide what you can reliably do.
The best, and most reliable connection is a single connection, source to sink without any switches, adapters, wall outlets, etc in-between. You can use a switch in some cases but it's going to be trial and error. 4k HDR can be very unforgiving with its connectivity so you need to keep that in mind.
Cable distance can also be an issue. You're best off to use Premium High Speed HDMI cables for your connections. They are not a 100% guarantee that they will work but at least you know they have been certified by HDMI.org to meet all of the HDMI 2.0 hardware specifications. The cable is just a data pipe. It's the HDMI chipset version in the source and sink that ultimately decide what you can reliably do.