I was hoping someone else may come along with suggestions, so I will try.
Do you watch the wireless performance in the Task Manager while this situation is happening? Do you notice the stream being interrupted or modified and not consistent? Does pausing the stream make any difference and do you show a buffer when watching the videos?
Do you have any settings related to QoS or bandwidth management that might be interfering?
Has there been any settings on your system or router where you set download speed limits? Since you have such a high Internet speed, does that need to be restricted.
I am reluctant to get involved with Networking problems because there are so many areas which might be involved. A Windows update can change settings you may not see or effect other software or even system performance which can cause problems.
On top of that, in many instances, just making some change may not be effective until something has been restarted or rebooted.
If you use Chrome, I would hope you would try other Browsers just to test.
