What interface does the monitoring flow through?

I figured out the problem, well at least I know why the wrong default gateway was being used. For whatever reason, the default gateway I created initially never actually updated the F5 configurations. I made a change the default gateway in the Network > Route GUI and after I press updated, the F5 started to send traffic out the Internal VLAN instead of the Management VLAN. This is all working as expected now. @cjunior Thank you very much for all of you assistance. When I ran the route -n command now, I get the 10.21.6.0 network as my default gateway not my 10.2.1.0 network.