For testing purposes, Can you create a solid color in layer 1, let's say Red for machine #1 and Blue for machine #2, then in advanced output can you create a new screen and change the input focus of that slice to layer 1, then make that screen output to NDI.
On each of your machine's can you open Newtek's Studio Monitor and select your Resolume source? Can you see the solid colors on the local machines?
If yes, then your NDI is working locally and your issue (among 95% of ALL NDI related issues) seems to be network related.
If no, then you have some sort of weird firewall issue most likely on your local machines.
If the first part works, lets move on to part 2.
Can your studio monitor see your other machine's solid color?
If no, then can you change the IP address of both machines to match settings but with a 1 number offset? example:
192.168.0.1 for machine 1 and 192.168.0.2 for machine 2.
Both machines to have a 255.255.255.0 subnet, and leave gateway blank.
Now connect both machines together via a ethernet cable (most modern NIC's will create an automatic crossover connection)
Give it a few min and can your Studio monitor now see both machine's solid colors?
If yes, then the problem lies in your router/switch.
For 99% of my gig's I would recommend using an unmanaged gigabit switch and not a router. I only use a router when I need to add wireless NDI sources or control (which isn't very often)
My money is on a bad setup in the router, or if the router has some sort of firewall on it.
Try to disable everything on that router so it basically becomes an unmanaged switch that passes out an address to connected devices.
Dumb question, on your current setup, are you able to ping the other machine?