Do you get the same errors if you run a test with only few users load like 5? The NL-Network-01 errors is a timeout issue from the server. It means that NeoLoad sent the request but did not get any response back after 5 minutes timeout.

It might be that your server is overloaded or i've also seen such issue when an antivirus was scanning all the request sent by NeoLoad and it lead to same errors. You can try to add an additional LG to see if you get same issues at same load with 2 LG's.

Also when you get those errors are you able to connect to your application from your localhost machine?