So I'm gonna add my tale to this thread.
I've been using this card since about 2012, and on 10.8, 10.9, it was perfect, on 10.10 and 10.11 it sometimes under heavy loads (copying GBs of files to/from the NAS) it would occasionally disconnect. I would have to toggle the wifi icon and restart my copies. After I updated to 10.12 I started seeing more serious issues. When I did have a connection, it was very slow, the rate (shown on the menu bar) would fluctuate anything from 1mbps to 2-300mbps all the time, making my life miserable. This is the current state of play for me, and I am wondering whether to update to 10.13 or just go 10.12.5->10.12.6. One other thing, I am using an airport extreme (not the last tower model, the one before) which I've also had since about 2011/12 and is not on the latest firmware (on purpose). This is another thing I could do to see if it's causing the issue.
BTW - when I reboot into win10, this card is flawless and super-fast. I can copy GBs between my NAS in minutes, not hours.
