Until yesterday, my wifi has been running perfectly for as long as I've had this system (many months). Since yesterday, it has been dropping every 20-30 minutes, and reconnecting automatically after about 30 seconds (usually on 2nd attempt).
I've looked at the many existing "wifi keeps disconnecting" questions on this site but none of them has solved my issue.
I've got a desktop with a wifi USB dongle, with very strong signal.
Taking advice from answers to similar questions, I've already disabled power management on wifi and USB, but the issue persists.
When the wifi drops, the command sudo journalctl -fu NetworkManager shows the following line:
NetworkManager[...]: <warn> [161...] sup-iface[0x...,wlx...]: connection disconnected (reason -14)
Is there a list of Network Manager reason codes from which I can see what -14 means?
14 NM_DEVICE_STATE_REASON_PPP_FAILED PPP failed
https://wiki.ubuntu.com/DebuggingNetworkManager/ReasonCodes
From the link above.