Turns out it was the length of the HDMI cable not handling the bandwidth. So I just got 4k HDR capable HDMI extenders and extended with some spare cables (which made it shorter). Works perfectly now. So for some cables anyways, 6 meters is too long. EDIT: I looked the size up just to make sure, it’s actually 7.5 meters (25 feet).
Amazon.com: HDMI Cable 50 ft - in-Wall High Speed HDMI Cord - CL3 Rated - Supports 4K, 3D, Full HD, 2160p with Ethernet - Audio Return - Latest Version - 50 Feet (15.2 Meters) : Electronics2.5mm, 3.5mm (also called headphone cables), and ¼” audio cables have a maximum distance of 150’ on average. Off-the-shelf, standard audio cables will be rated with 150’ in mind. It is possible to go further by custom-making something using thicker cable than usual. The lower the AWG, the greater the distance you can go.
This calculator allows for the selection of a voltage drop of up to 3% on a circuit run. Minimum cable size can be calculated based on cable length, voltage, amperage, and acceptable loss. This cable sizing tool suggests THHN, which is appropriate for standard industrial applications. Wire selection must be in compliance with NEC Code Article 300.Cable Matters Certified 8K @60Hz Fiber Optic HDMI Cable 49.2 ft / 15m. $140. BUY FROM AMAZON. If you need a really long HDMI cable, then it needs to be "active," as traditional passive HDMI cables . 113 275 403 419 367 305 210 371