Link Failover of Unidentified role between Port1 & Port2 (extended Network & MPLS)

Fortinet Support Team, 

This is my 1st post in fortinet forum, so request you to ignore my language mistake.  1st giving brief info of setup  Device FD100-D

Using 2 WAN connection and fail-over is configured properly.  Port1 (Unidentified) - Extended RF connectivity to connect my remote location via P2P RF Device

Port2 (Unidentified) - MPLS connectivity to connect my same remote location as previously said with Last mile RF Setup. 

           Port1 given high priority in Static Route configuration and Port2 has 2nd priority. 

Question - I want to configure such a way that if Port1 is down, then automatically my configured traffic goes to Port2. Internet traffic should not affected as WAN ports are different.  I also configured WAN Monitoring for Port1 & Port2 but it doesn't work when Port1 is down.   Is this possible to configure Failover between Port1 & Port2?  Help would be really appreciated.