FME Server on Azure: Unable to run jobs when using internal or private Azure Load Balancer

Symptom

When FME Server is deployed in Azure with the Azure Load Balancer, and the load balancer is internal, or private (the load balancer does not have a publicly accessible IP address), FME Server may work intermittently or not at all.

If there is only one FME Server core/web VM present behind the Azure Load Balancer, the FME Server web ui will be accessible from other VMs, but no jobs will run. From the FME Server core/web VM, the FME Server web ui will not be accessible.
If more than one FME Server core/web VM is present behind the Azure Load Balancer, FME Server may work intermittently.
 

Cause

This is a limitation of Azure Load Balancer (internal/private).

Accessing the Load Balancer from the same VM and Network interface.  

When FME Server is accessed from the core/web VM, the web ui will not load.
Submitting jobs from an accessible web ui will fail, as the FME Server core will be making a request to itself through the load balancer.
 

Resolution

1. Add a second NIC to FME Server Core virtual machine(s)

This blog outlines workarounds to this limitation.
Adding a second NIC to the FME Server core/web VM, and routing outbound traffic through the second NIC resolves this issue.
For steps, please refer to Azure documentation:
Add network interfaces to or remove network interfaces from virtual machines.
Configure the VM operating system to use multiple network interfaces properly: Windows Linux

2. Use Azure Application Gateway

Azure Application Gateway is a web traffic load balancer that enables you to manage traffic to your web applications. It does not have the same limitation as Azure Load Balancer.