This is what I use, once a week. I just checked and cockpit on my standard Ubuntu Server installation has the same update issue. I will look into this as this doesn’t make much sense, being cockpit most useful as tool for a headless server, not a workstation.
I’m not sure how many users this affects and peoples skill levels, but at least if we can document what is found people can work through the solutions and grow knowledge.
You are right, what I proposed doesn’t work. I tested again and refreshing the package cache in cockpit fails. What works is disabling NetworkManager for good:
But then the cockpit ‘network’ tab doesn’t show any information, and I prefer to have cockpit show network configuration and usage info instead of being able to update packages.
One workaround could possibly be to set up a dummy network interface. I’ll look into this tomorrow.