A:Answer You would be able to stream 4K Netflix from your 4K Blu-Ray player through this device to your 4K TV. However, you should already be able to do that without this device.
If you cannot do that now, I would not expect that this device fixes that issue for you.
Ensure you are using the latest HDMI cable, that you subscribe to Netflix 4K services, that your Blu-Ray player can output Netflix in 4K, and that your TV accepts 4K signal in the HDMI port you are using.
I would suspect that your Blu-Ray player does not output Netflix in 4K.