When placing the network monitor on the desktop, you are free to setup the update interval using the panels controls or by using the 'network monitor settings' popup menu. But, when it is placed there for a longer time (didn't check if just a logout is sufficient), the 'update interval' input field is gone. Just a radio button for selecting/deselecting the interface is left over. Reproducible: Always
i stumbled upon this bug report because i was trying to find a way to change the refresh rate but only found a list of network interfaces in the settings. So, in my case, the update interval setting was never there to begin with. Even when I add a new widget and immediately go to settings. reproduced on opensuse leap 42.1
still requires a fix in plasma5/fedora25
There is now an update interval setting.