Having the same issues. I have a gigabit NIC. I am using cat 6a ethernet cable. My switch is a gigabit switch. Worked likea charm when I was using Optimum online. I have the 600Mbplan. If i use a wifi extender i get around 175Mb. Using just straight wifi i get around 600Mb. With my PC hardwired to the xFi router I am only getting 89Mb. I alreadey replaced the cabling to see if it made a difference.