Alright, I'll try to explain everything that is going on here and maybe one of you has dealt with all of this before. I've played with vMix at home, which worked great. Now I'm not working on my network, and I have to comply with the engineer.

In order to get audio from our soundboard (all IP on its own VLAN) I need one network cable. I will get that audio via Dante virtual sound card. But that's all I'll get from it. They don't want me streaming or running NDI cameras on this VLAN.

I will need to plug in another cable from our general internet network which will provide the box the ability to plug NDI cameras, along with internet access to stream out. They have a very limited number of IPs for this network and are saying they cannot give me dedicated IPs for my NDI cameras (all PTZOptics). PTZOptics cameras have an IP tool that allows you to flash the camera with a new, fixed IP. Does this work on the local end without them assigning me an IP? Would just a dedicated IP for the computer itself on their end suffice?

Did not want to have two separate networks as I'm sure it complicates everything, but wanted to see if anyone has worked with two like this, and how dialing into vMix Social has worked for you?

Question is should I have two network connections (one for audio, the other for NDI and Internet) or three (one for audio, one for internet, one unmanaged switch for NDI).

If anyone understands what I just said, I appreciate your help. Thank you!!

If money isn't too big an issue, you can install a rednet card into the system to use as your audio interface. Basically a NIC that shows up as an audio interface and takes in Dante at ultra low latency.

A good and powerful switch that supports everything doesn't have to be expensive. It starts from 40$.
I would get a mikrotik router. That supports almost everything that you can think of.
https://mikrotik.com/product/hex_s
should do it.
A fantastic PoE Switch that I work with is
https://mikrotik.com/product/crs112_8p_4s_in

Esentially you could just use the switch as it supports routing as well but is not specifically build for that task.

NDI/Network delay. Make sure you have enough bandwidth available. A gig network can be utilized fully just with a few NDI sources as each can got as high as 100-120 Mbit/s. Having 5 or 6 cams can saturate the network already. Make sure the MTU is set correctly. If set too high packet fragmentation will be done by the NIC which will throttle the NIC throughput.

PTZ Optics cameras are NDI-HX, which is < 20 Mbps per stream. Not full NDI, which would be >120 Mbps.

Also, you can add a second (or third) NIC to your vMix hosts. NDI automatically aggregates the available connections.

That sounds a bit like magic. I haven't tested, but the computer usually follows the lowest metric setting to prioritze traffic. A 2nd or even 3rd connection normally wouldn't be utilized if not combined at the network layer into a single virtual interface. Or added into manual routes to make use of them.

I'm not that deep into NDI in that regards but would like to expand my knowledge. Please share more details on the mechanisms how NDI detects and used multiple NIC to aggregate bandwidth.

It's not random. It's the metric that dictates what NIC is used. The cheapest path first. You can reduce/add costs by changing the metric. You can have a look at all this on a windows machine by typing route print into cmd.