Sonoma external Hub only 30Hz

LG appears to be a 4K display with displayPort and HDMI inputs

Toshiba appears to be a 4K display with 3 HDMI 2.0 ports

Anker dock : 2*HDMI: 4k@60Hz & 4k@30Hz

the port closer to the free end is labeled 60Hz, the port closer to the cable-end is labeled 30 Hz.

(On Mac, only one can be used at a time).

Selore SEUC3908:

1*HDMI 1: 4K@60Hz(3840x2160) (closer to cord)

1*HDMI 2: 4K@30Hz(3840x2160) (closer to end)

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IMPORTANT:

Certified "PREMIUM" cables recommended in all cases.

Later MacOS is More demanding that older versions.

.

HDMI cables you want for HDMI-only Displays (higher resolutions than 720p TV sets) are marked as Certified with an anti-counterfeiting tag and are labeled:

"Premium High Speed HDMI cable" or that + "with Ethernet" --OR--

"Ultra High Speed HDMI cable" or that + "48G"

Cables with No Certification tags are good for your standard 720p TV set, and not much more.

HDMI was invented for HD TV sets. it works great at its original resolution of 720i or 720p. At higher resolutions, it quickly develops issues that are complex to solve, and the cables and adapters required to solve are NOT intuitive.

Then you have exhausted all the typical reasons it might not be working.

standard debugging technique going forward would be to substitute "known-good" components for items that are interchangeable, in hopes os seeing the problem follow one particular item, thus isolating the issue to one thing.

maybe a new cable?

Hash70--

later versions of MacOS are becoming much more fussy about transmission errors. If the display reports any transmission errors, the display will be reduced in resolution or refresh rate or go dark.

Better cables are essential.

Same here,was showing upto 120hrz at 1080p to my lg oled before I updated to sonoma now the refresh only shows 25/30hrz