I just went through hell trying to figure out the per app addressing and my conclusion is, you are best to use separate NIC’s with separate subnets and create a vlan for each NIC and do all the trickery on your switch
or
Install TrueNAS on Proxmox and create a bunch of Lan connections and do the same thing.
Creating Alias addresses and assigning them to an App does not work as one would like, its not the same thing and does not work like it would with a VM on a Hypervisor, maybe it can, I don’t know my own backside from a Docker container, its all witch craft to me, but I know TrueNAS with Docker just does not work like Proxmox with VM’s or LXC’s so trying to make TrueNAS a network switch for these Apps just doesn’t work.
Creating multiple Alias addresses creates major issues on my Ubiquity Layer 3 Switch and most of the time the additional addresses are just not registering on the Switch and pop in and out of existence, I think its triggering some sort of Spanning Tree safe guard in the switch.
My fun with this topic: Fangtooth Apps and Multiple Nics - #23 by NexGen3D