@jdaviescoates Thank you, much appreciated.
@joseph Many thanks for the reply.
@joseph said in server seems to be going to sleep and becomes inaccessible:
Did you install anything on the server recently?
Nope I didn't install anything manually (say via ssh or otherwise). The only thing I did was to reboot the server from the Cloudron interface to complete updates as per notifications (I did not run the update manually on the server).
@joseph said in server seems to be going to sleep and becomes inaccessible:
Are you saying the server has gnome/xfce/kde?
Yes it looks like it's got Gnome...
Can see it even in the thumbnails from Netcup SCP interface:

VS
on another server.
@joseph said in server seems to be going to sleep and becomes inaccessible:
Maybe you can check if those packages are installed?
Seems like there are both Gnome and power management packages installed....which is freaking insane.
root@v2202108132182160313:~# dpkg -l gnome*
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name Version Architecture Description
+++-========================================-=======================-============-===========================>
un gnome-applets <none> <none> (no description available)
un gnome-backgrounds <none> <none> (no description available)
un gnome-bluetooth <none> <none> (no description available)
ii gnome-bluetooth-3-common 46.0-1ubuntu1 all GNOME Bluetooth 3 common fi>
ii gnome-bluetooth-common 3.34.5-13build3 all GNOME Bluetooth common files
un gnome-calendar <none> <none> (no description available)
un gnome-characters <none> <none> (no description available)
ii gnome-control-center 1:41.7-0ubuntu0.22.04.9 amd64 utilities to configure the >
ii gnome-control-center-data 1:41.7-0ubuntu0.22.04.9 all configuration applets for G>
ii gnome-control-center-faces 1:46.4-0ubuntu0.24.04.1 all utilities to configure the >
ii gnome-desktop3-data 42.9-0ubuntu1 all Common files for GNOME desk>
un gnome-documents <none> <none> (no description available)
un gnome-icon-theme <none> <none> (no description available)
un gnome-icon-theme-symbolic <none> <none> (no description available)
un gnome-initial-setup <none> <none> (no description available)
ii gnome-keyring 40.0-3ubuntu3 amd64 GNOME keyring services (dae>
ii gnome-keyring-pkcs11:amd64 40.0-3ubuntu3 amd64 GNOME keyring module for th>
un gnome-maps <none> <none> (no description available)
ii gnome-menus 3.36.0-1.1ubuntu3 amd64 GNOME implementation of the>
ii gnome-online-accounts 3.44.0-1ubuntu1 amd64 service to manage online ac>
un gnome-packagekit <none> <none> (no description available)
un gnome-panel <none> <none> (no description available)
ii gnome-remote-desktop 42.9-0ubuntu0.22.04.2 amd64 Remote desktop daemon for G>
un gnome-session <none> <none> (no description available)
ii gnome-session-bin 42.0-1ubuntu2 amd64 GNOME Session Manager - Min>
ii gnome-session-common 42.0-1ubuntu2 all GNOME Session Manager - com>
un gnome-session-flashback <none> <none> (no description available)
ii gnome-settings-daemon 42.1-1ubuntu2.2 amd64 daemon handling the GNOME s>
ii gnome-settings-daemon-common 42.1-1ubuntu2.2 all daemon handling the GNOME s>
un gnome-settings-daemon-schemas <none> <none> (no description available)
ii gnome-shell 42.9-0ubuntu2.2 amd64 graphical shell for the GNO>
ii gnome-shell 42.9-0ubuntu2.2 amd64 graphical shell for the GNO>
ii gnome-shell-common 42.9-0ubuntu2.2 all common files for the GNOME >
un gnome-shell-extension-appindicator <none> <none> (no description available)
un gnome-shell-extension-autohidetopbar <none> <none> (no description available)
un gnome-shell-extension-caffeine <none> <none> (no description available)
un gnome-shell-extension-dash-to-panel <none> <none> (no description available)
un gnome-shell-extension-dashtodock <none> <none> (no description available)
un gnome-shell-extension-desktop-icons <none> <none> (no description available)
un gnome-shell-extension-desktop-icons-ng <none> <none> (no description available)
un gnome-shell-extension-multi-monitors <none> <none> (no description available)
un gnome-shell-extension-pixelsaver <none> <none> (no description available)
un gnome-shell-extension-prefs <none> <none> (no description available)
un gnome-shell-extension-taskbar <none> <none> (no description available)
un gnome-shell-extension-top-icons-plus <none> <none> (no description available)
un gnome-shell-extension-ubuntu-dock <none> <none> (no description available)
un gnome-shell-extension-workspaces-to-dock <none> <none> (no description available)
un gnome-shell-extensions <none> <none> (no description available)
un gnome-shell-pomodoro <none> <none> (no description available)
un gnome-software <none> <none> (no description available)
un gnome-sound-recorder <none> <none> (no description available)
ii gnome-startup-applications 42.0-1ubuntu2 amd64 Startup Applications manage>
un gnome-terminal <none> <none> (no description available)
un gnome-themes-standard-data <none> <none> (no description available)
un gnome-todo <none> <none> (no description available)
ii gnome-user-docs 46.0-1ubuntu1 all GNOME Help
un gnome-user-share <none> <none> (no description available)
un gnome-weather <none> <none> (no description available)
root@v2202108132182160313:~# dpkg -l power*
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name Version Architecture Description
+++-=====================-============-============-===================================================
ii power-profiles-daemon 0.10.1-3 amd64 Makes power profiles handling available over D-Bus.
ii powermgmt-base 1.37 all common utils for power management
@joseph said in server seems to be going to sleep and becomes inaccessible:
This is a DNS resolution error. DNS is not working, test with host api.cloudron.io .
Right so, this seemed to happen as the server wakes up and then it becomes fine (all apps healthcheck fine). I did change the DNS config (i.e. added IPv6 as explained above) so maybe propagation wasn't yet perfect. Anyway I can't see how any of this would be related to the server suddenly a DE 
I let the logs open all night and while I can see a pause between 23:37 and 8:30, there are no more DNS errors and the servers has remained up since 8:30. So there are progress. Though in the Cloudron Dashboard it says a backup was completed at 01:10 but I cannot see that in the log...?
Feb 11 23:37:00 box:apphealthmonitor app health: 19 running / 3 stopped / 0 unresponsive
Feb 11 23:37:10 box:apphealthmonitor app health: 19 running / 3 stopped / 0 unresponsive
Feb 11 23:37:20 box:apphealthmonitor app health: 19 running / 3 stopped / 0 unresponsive
Feb 12 08:30:30 box:apphealthmonitor app health: 19 running / 3 stopped / 0 unresponsive
Feb 12 08:30:40 box:apphealthmonitor app health: 19 running / 3 stopped / 0 unresponsive
Feb 12 08:30:50 box:apphealthmonitor app health: 19 running / 3 stopped / 0 unresponsive