Setting up redundant isps between two fortigates

[mrjameselmore01]

Hey Folks  I was hoping I could get some help on the best practices on setting up 3 ISPs in an SDWAN configuration from my 100F to my 60E at a remote site that houses a few servers . 

 I have a 5g modem  , att fiber connection and spectrum business service all plugged into my 100F firewall .

 Wan1 Spectrum

IPSECTUNNEL1

 Port11 ATT Business

IPSECTUNNEL2

 Port12  ATT 5g

IPSECTUNNEL 3

I have 3 ipsec tunnels built between the two fortigates as well and they are all the same phase 2 selectors .

All I am trying to do is put the 3 ips into the SDWAN and have the fortigate fail over from 1 downed isp ( wan1 wi/ ipsectunell1)  to the second Wan connection  (Port 11, ipsectunnel2)  etc  .  I've tried setting this up once and had issues with different communication going over different isps when all I want is all the communication going over 1 isp and one tunnell until the need to fail over.  I've been knocking my head on a wall looking for this exact scenario and how to set it up the easiest way . Any help is appreciated.

[AEK]

You can set the SD-WAN rules like this:

• 1st rule: Src: all. Dst: remote-subnet. Strategy: Manual. Interface: IPsec1
• 2nd rule: Src: all. Dst: remote-subnet. Strategy: Manual. Interface: IPsec2
• 3nd rule: Src: all. Dst: remote-subnet. Strategy: Manual. Interface: IPsec3

Do the same on the remote FGT.

Once IPsec1 is down, traffic fails-over to IPsec2, and so.