Netflix buffering has nothing to do with display port type (except that your laptop now sees display with better resolution).
What is your ISP package? What is your laptop' model?
Thank you for your quick response. I am not very knowledgeable about computer stuff, in fact a complete novice but learning all the time.
My laptop is HP Elitebook 8540P.
I have fibre broadband 100Mbps unlimited. Tech type UFB 100/20 with a Fibre mode NF4V modem. Everything works fine on my older Compaq laptop using only HDMI cable, no problems at all which is why I thought the problem must be the new adapter with the newer HP laptop. I hope this makes sense to you and I do appreciate your help. Thanks from Linda