After NAC restart, the console is not available. If the browser Web Developer Tools are opened and communication with the server is investigated, you can see that login.jsp cannot be loaded (0 bytes are transferred from the server).
Nolio 6.8
Bug in the NAC server.
Stop all NES servers, restart NAC server (should start successfully), then start NES servers.
The bug is fixed in Nolio 6.9.2.