No network despite working network

[snomos]

Helping a customer to get speller to work, using video/screen sharing:

• window pops up, menus are visible
• display menu is stuck on All Languages
• the rest of the window is grey, and stays grey
• restarting Divvun Manager did not help
• the network was obviously working, since video and screen sharing worked

This seems to indicate that there are issues with the network connection. It seems very fragile, an impression that is not new. There are many reports that the window is blank.