This got closed on AskUbuntu because it wasn't Ubuntu enough for them.
I don't have any WLAN connections set up, and I always connect via Ethernet cable. However my computer has a small light on it that flashes to indicate network activity. For some reason this light keeps flashing, at extended random intervals, which is very annoying. I remember that I disabled it somehow on my old partition (Ubuntu, Mate), but I'm not seeing an option for it now.
Added: since asking I found an answer to the LED problem here: "Wireless indicator light flashing for activity on laptop keyboard" but I would feel slightly better knowing that I solved the source of the problem and not just the symptom.
Then I tried
sudo rfkill block all. Will that solve it permanently? Is there a better way?