Try disabling hardware acceleration? I think it’s turned on by default.
If you haven’t already, try on a different youtube account.
If that doesn’t work, Have you tried doing all 3 of those things you’ve listed at the same time?
Do you have other devices in your household, and if so do they have the same issue?
If yes, you might want to check your router settings, or factory reset it. If that still doesn’t work it may be an issue with your ISP.
If no, you may need to reinstall Windows if no one else can provide a good solution. You can always try a virtual machine to test and see if it works there first.
Try disabling hardware acceleration? I think it’s turned on by default.
If you haven’t already, try on a different youtube account.
If that doesn’t work, Have you tried doing all 3 of those things you’ve listed at the same time?
Do you have other devices in your household, and if so do they have the same issue?