Have an Apple genuine Thunderbolt Gigabit adapter. Just recieved the new gigapower speeds from Uverse. I have 2 desktops hardwired in that are getting 950 up and down. With the gigabit adapter on my 2015 Macbook Pro, I only recieve 500 up and down. Tried different cat 6 cables and still the same. Any thoughts? Or just a defective adapter?