The KDE System Monitor network page seems to be broken and does not show any network transfer rates. I used to use the Network Speed widget added to the bottom default panel, but it also stopped working a month or two ago. Perhaps there is some low-level network monitoring support lib that is no longer working or not available.
What other options are there for some kind of gui based real-time network i/o monitoring on my Plasma desktop?
Both are working fine for me when I run an internet speedtest.
Are you fully updated to the latest kernel 6.12.7, etc…?
If you have btrfs snapshots enabled, you could rollback to an earlier snapshot where you know it works, and figure out the breaking packages from there on, to report the problem.
Thanks for your commet. As it turns out I did a fresh install of the 241110 ISO yesterday on a new minipc and the Network Speed widget works fine again. My previous system was a few years old so I’ll just put it down to… old age.