So I have multiple laptop/desktop setups for broadcast and I used NDI Tools for my video transmits and receive. Some NDI Sources shows up but there's also a NDI Sources that doesn't show up. I have updated my Windows version on all of my laptop/desktop and we have a static/private network. You can see the attached file that the Studio Monitor only sees one NDI Sources. But I have my other machines open and currently using NDI.
I'd try adding the other systems IP as an External Source in NDI Access Manager and see if that gets them to appear. If it does, then something on your network is blocking mDNS traffic.
You might also try my NDI Source Discovery tool and see what that shows.
https://kanelp7.wixsite.com/kanesworld/ndi-source-discovery
You might also try my NDI Source Discovery tool and see what that shows.
https://kanelp7.wixsite.com/kanesworld/ndi-source-discovery
Sorry for the late response. So I have used NDI Source Discovery and Analysis but I don't know how those programs work. But the problem still persists until now even if I'm on other locations and I'm using NDI via vMix. The problems stays the same, but when I use NDI Access Manager, the NDI will show but after a while it disappears.
When you use NDI Access Manager, what exactly are you doing with it that gets them to show up?
I go to External Sources and add all the IP address of the NDI Sources. And on the Advanced tab, it goes by default. Once I've added the IP, it shows for a short period of time like an hour then it freeze on vMix and will disappear on the network so I restart the device to access again the NDI Source and it'll appear again on the network.
Problem still persist. All of our computers are having the same problem.
I'd really try setting up Discovery Server and see if that helps. If you are having to use External Sources to get devices appearing, then something is blocking the mDNS protocol from working on your network which is how NDI tries to work by default.
To use Discovery Server, run it on one of your Windows PC by going into "C:\Program Files\NDI\NDI 6 Tools\Discovery Service" and running the executable there. You will see a console window appear saying the server is running on port 5959.
Make sure no NDI application are currently running or open on the computer. Then open NDI Access Manager. In the Advanced tab, enable Discovery Server and enter the IP address. You must do this on all of the systems.

To use Discovery Server, run it on one of your Windows PC by going into "C:\Program Files\NDI\NDI 6 Tools\Discovery Service" and running the executable there. You will see a console window appear saying the server is running on port 5959.
Make sure no NDI application are currently running or open on the computer. Then open NDI Access Manager. In the Advanced tab, enable Discovery Server and enter the IP address. You must do this on all of the systems.

I'd also remove the External Sources you have manually entered, just so you are only testing with Discovery Server.
Once you have this setup, when you start an NDI application you should see an entry appear in the Discovery Server console display. See if things work correctly.
Once you have this setup, when you start an NDI application you should see an entry appear in the Discovery Server console display. See if things work correctly.