Once you've started watching something Netflix will try and compensate for a drop in connection speed by dropping the picture quality rather than buffering. Netflix recommend a minimum of 5mbit for streaming HD and 25mbit for streaming 4k. My connection speed is quite variable in the evening when everyone else in the street who's on Virgin is using the internet but that's expected.
Massage an ego, click the kudos button. If someone answers your question, mark it as helpful. Be nice, eat all your vegetables and keep your room tidy.