Pi 4 with Ubuntu 22.04 runs fine for several hours after boot, serving as an access point and a DHCP server. The next day it sits there unresponsive — DHCP stops, SSH is unreachable, and the AP can't be connected to. There is also no video output (which could be the result of the display output going to sleep and subsequently being unable to wake up from input devices).
Both LEDs are solidly lit in this state, as well as the Ethernet port (no rapid blinking). The CPU is not hot. A power cycle restores it to working condition.
Update
There was a systemd-logind[831]: System is rebooting. message in the full journal, but no clues as to why. I don't issue any reboot commands to this machine myself — it's supposed to be always on.
So there are two problems:
- It reboots itself (?)
- It freezes when it does so
Original journal inspection
The last lines of journalctl -k -b -1 seem to be the same upon the next boot whenever it occurs:
jan 02 03:40:07 rpi kernel: rfkill: input handler enabled
jan 02 03:40:09 rpi kernel: device wlan0 left promiscuous mode
jan 02 03:40:09 rpi kernel: br0: port 2(wlan0) entered disabled state
jan 02 03:40:09 rpi kernel: ieee80211 phy0: brcmf_vif_set_mgmt_ie: vndr ie set error : -52
jan 02 03:40:09 rpi kernel: ieee80211 phy0: brcmf_vif_set_mgmt_ie: vndr ie set error : -52
jan 02 03:40:09 rpi kernel: ieee80211 phy0: brcmf_vif_set_mgmt_ie: vndr ie set error : -52
jan 02 03:40:10 rpi kernel: brcmfmac: brcmf_cfg80211_set_power_mgmt: power save enabled
jan 02 03:40:23 rpi systemd-shutdown[1]: Syncing filesystems and block devices.
jan 02 03:40:24 rpi systemd-shutdown[1]: Sending SIGTERM to remaining processes...
(br0 is the wlan-ethernet network bridge)
I'm not sure how to interpret it exactly. Seems like a controlled shutdown...maybe?
Also the WiFi looks to transition to power saving — is that a reason for concern with regards to these symptoms? I can find no power management options in the Settings app apart from the Balanced / Power Saving profiles, and I'm on the former. I'm assuming therefore that there is no meaningful power management that can be configured by users in this release.
The access point's Network Manager connection has 802.11 power saving set to default.
The journal time stamps aren't exactly reliable I'm afraid, so I don't know exactly when things happen.
