In plain language
Instead of copying the display, you pick a table. Each table describes a specific combination: a maximum resolution and frame rate, a chroma and bit depth, an HDR set, VRR on or off, and an audio channel count. The source reads that and behaves accordingly.
Why it matters in your setup
A fixed table is the fastest way to make a chain repeatable. If you suspect the negotiation is the problem, drop to a known conservative table — say 4K60 4:4:4 with stereo audio. If it works, the chain is fine and something in the EDID was the issue. Then climb back up one step at a time.
It is also how you deal with a display that reports itself badly. Rather than fighting a broken EDID, you replace it with one that describes what the screen actually does.
What the DR HDMI 8K does with it
The DR HDMI 8K carries 100 tables: ten custom slots plus ninety presets running from 8K60 4:2:0 FRL-5 with VRR and HDR down to 480p60 stereo. Selecting one loads it immediately and fires a hot-plug event so the source re-reads it. You can also upload your own EDID binary into a custom slot, or save the EDID currently in use into slot 8, 9 or 10.
Need the hardware?
Open the DR HDMI 8K product page on HDfury.uk.