Streaming Netflix 4K

Hi everyone,

New Mac user here having just bought the IMac 24.

My internet speed is super fast Virgin Fibre showing 220-290mbps, upload 21-24mbps

i have premium Netflix and all the settings set to high, but I simply cannot stream 4K. I’ve tried the control + D thing and it’s only showing 1930x1080.

Youtube is fine at 4K and the Mac screen looks stunning. So is this a problem at Netflix end?

I’ve spent all week searching online and I’m at a brick wall.

Any help would be greatly appreciated from a new user who you can tell knows very little about Macs