You are experiencing excessive packet loss on one of your two WAN links route traffic...

 AppQoE is an AppSecure component that provides application quality of experience by monitoring the network performance and dynamically adjusting the traffic routing based on predefined policies1. AppQoE can detect excessive packet loss on a WAN link and route the traffic to another link that has better performance2. AppQoE can also prioritize the traffic based on the application type and user group3. AppQoE is suitable for accomplishing the task of routing traffic from the degraded link to the working link.

The other options are not correct for the following reasons:

AppFW is an AppSecure component that provides application firewalling by enforcing granular policies to allow, deny, or limit access to applications based on user roles, locations, and devices4. AppFW does not monitor or adjust the traffic routing based on network performance.

AppQoS is an AppSecure component that provides application quality of service by allocating bandwidth and shaping traffic based on application priority and user group. AppQoS does not monitor or adjust the traffic routing based on network performance.

APBR is an AppSecure component that provides application-based routing by selecting the best path for each application based on predefined criteria such as latency, jitter, packet loss, and cost. APBR does not monitor the network performance dynamically or adjust the traffic routing automatically.

References: AppSecure Overview Understanding AppQoE Configuring AppQoE Understanding AppFW [Understanding AppQoS] [Understanding APBR]