I have a running Google Node single file server, but Grafana panels do not work

I just set up a single-node Google file server, hoping to do a "final run" to fix my Google Storage Bucket problems.

The SNFS seems to be working, until now, but the Grafana panels to monitor the thing do not seem to behave as advertised:

I can log in to the Grafana server and I can change the administrator password from the initial default. But when I try to navigate to the "System" or "Storage" panels, my browser presents a pop-up window, several times, and gives the user ID "admin" with the new password or the initial one produces exactly the same result as clicking "cancel": pop-up messages with "Template start error" and "Unauthorized" and blank graphics with "unauthorized" marks:
Screenshots of what happens.