Hi. I have a 2017 15" MacBook Pro (2.9Ghz i7). I am lucky enough to have 1 Gb Internet service to my home. Despite having now tried 3 different 'Gigabit Ethernet Adapters" I am unable to achieve more than about 560Mb download. This is with my laptop (temporarily) plugged directly into the fibre-optic box (so removing any home network delays). My service provider came to check the connection and using a rather old Dell laptop, he managed over 900Mb when my laptop managed only 560Mb. I have to say that is annoying! Suggestions?