I may have stumbled on a workaround for the disconnection issue, though I can't be sure.
To narrow down the time when the connection stops working, I left a ping to my router running, every 4 seconds.
ping -i 4 192.168.1.1 > ping.log
Several days later, I rebooted, forgot about the ping, and had the connection fail a couple of times that day. Whenever the ping has been running, the problem has not occurred; but of course, the incidence of problems is sufficiently low that it might be a coincidence.
I may have stumbled on a workaround for the disconnection issue, though I can't be sure.
To narrow down the time when the connection stops working, I left a ping to my router running, every 4 seconds.
ping -i 4 192.168.1.1 > ping.log
Several days later, I rebooted, forgot about the ping, and had the connection fail a couple of times that day. Whenever the ping has been running, the problem has not occurred; but of course, the incidence of problems is sufficiently low that it might be a coincidence.