I've got a Fortigate 60E v6.4.9build1966(GA) and am running into slow internet (both up and down) on a new install. I've got a fibre 1G/1G that I tested without the fortigate and was able to get advertised speeds.
I'll list what I've done to see if there's anything I'm missing or doing wrong:
setup admin profile - user and suser profiles
setup network interfaces
WAN - using ISP IPs they provided
LAN - our internal netowork
setup static route - setup the route from LAN to WAN
setup firewall policy - as a test, everything was set to allow all, flow-based, and no security profiles
I've checked the ports: 1G full duplex at both ports, auto-negotiate, and both set to physical ports
As a "just in case" I tried to slip a gig dumb switch in between and it did not help. There was a mention of TCP saw-toothing where the unit couldn't keep up with the burst in the knowlege base. But implementing it didn't help. I'm hoping there's something else I'm missing that will help with my situation. Thanks in advance!
I finally figured out what was going on. The laptop I was using had a 10/100 port, and for some reason, it slowed everything down to 10. Not entirely sure why this was happening but swapping to a 10/100/1000 port fixed it.