So I Have an RB3011UiAS-RM Router and a 500 Mbps ISP Connection.
I've configured my Router with FastTrack too and I'm only getting a max of 350 Mbps Speeds.
When I've tried plugging in my laptop directly to my provider's modem, I am able to get the full 500MBPs
I Have also configured FastTrack on my Route rand it's on the very top of the list in my Firewall Panel but I'm still getting a maximum of 350 Mbps.
Sometimes when I run a Speed Test, It starts at 450 Mbps and immediately drops down to 350 Mbps or even less (keeps dropping throughout the whole test)
Before I bought the Mikrotik I confirmed that it can handle a 500 Mbps connection easily.