we have a fortigate 60 D on the perimeter through which clients connect to internet through PPPoE. Was initially running on lower firmware , however upgraded it recently to version 5.1 patch 10. things were looking ok so further updated to 5.2.2,. Had issue with internet traffic not working for internal clients so , downgraded back to 5.0.10. ever since then the speed of the internet is very slow. we have a 100mb connection and checking on the modem directly gives a pretty good throughput. However when the line is connected to the fortigate unit from the ISP directly , the speed is hardly reaching 1mb.
The downgrade of the firmware was done through the web manager only.
Have run diag on the interface running the adsl connection and didn't find any errors showing up in the output result.
what is going wrong ??
Ran a diag flow. looks like packets are not reaching wan2 interface at all and are going through wan1 only. Also tried changing the distance of wan1 and wan2 to same and making the priority of wan1 to 1 and wan2 to 0 so that wan2 gets used by default. however still seems to use only wan1.