

Since posting this, I’ve also tried installing powertop and checking the tunables. According to lsof -t
, the dongle is connected directly to the root hub (under only xHCI host controller). I noticed in powertop that those controllers were still under power management, so I disabled them. That didn’t seem to help. The keyboard still lost connection.
These are the dongles that came with the keyboards, so they’re paired out-of-the-box (although I have also used the process for re-pairing them). They are just connected to a USB port on the computer, so not really permanent, but I do leave them connected. Not both at the same time, but each in turn. Hope that answers your question, but I’m not 100% sure I understood it.