I am going to try and be helpful. 4k streaming is a bit complex. Here are some questions to ponder:
1. Are you attempting to stream 4k content via Netflix over a VPN (virtual private network, such as Nord VPN or IP Vanish, etc.) and perhaps streaming from a region where 4k content is not available?
2. Have you checked your Netflix app settings (and the settings on the Netflix website itself) to make sure the highest quality setting is enabled for content? I am assuming you have done a speed test on your network and determined you have the bandwidth. Another thing related to this is ensuring your network drivers have been updated (I think you said you did that already). Additionally, you could check to make sure you are not on a metered connection by right-clicking your wireless icon and checking the Properties tab in Windows. Another way you could be metered is by your internet modem/router inadvertently or intentionally interfering with your speeds. Check out this webpage for Quality of Service (QoS) settings that might help you. How to Use Quality of Service (QoS) to Get Faster Internet When You Really Need It (howtogeek.com)
3. You confirmed you tube 4k works, but have you confirmed any other 4k streaming content services? Example: Amazon Prime has 4k content, try that?
4. Have you tried playing a 4k video from your local machine? Example. Transfer a 4k video from your cellphone or other device that you captured yourself. Or maybe download a 4k test video onto your hard drive from somewhere and play it locally to see if its working. To play all kinds of video formats, check out VLC media player. Hands down the best there is out there and it will play anything you throw at it (practically).
Those are just some of the things I could think of right now to try and help. Good luck!
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