Please consider the picture below. I have installed the xfce widget for network load monitoring but in the settings there is no option to select which network adapter is uses. By occasion, system has select one of non-active interfaces.
I have been looking for a dropdown with network interfaces selection and have overseen the input field. I needed though to lookup the connection wihh
ifconfig as the UI network monitor was showing a verbose message like "cable connection #3"
In the picture it's the freetext input field Netzwerkschnittstelle.
So I pasted the adapter name like
abc1234abcdef and now it works!