Expected Behaviour:
I'm running two Pi-holes on default installs in virtual machines on top of Proxmox. Hole1 is Ubuntu 18.04 based install and Hole2 is based on 20.04. Both installs usually work well and have the same general setup except for the Ubuntu version. They are set as default DNS servers for the home network. Both have 4GB of RAM and two cores of a i5-4570 CPU and a healthy 32 GB portion of an M.2 sata ssd. According to proxmox both installs are fine and working as intended.
Actual Behaviour:
Sometimes randomly, maybe once a week, and sometimes after a reboot one or two of the Pi-holes fail to resolve any DNS. Usually I only notice this only when both of them fail. Today I was checking my setup and noticed that hole1 was not resolving anything. Is there something I can do to resolve these random hiccups? The problem can always be solved manually by changing any Upstream DNS Server in the settings.
I have a mobile Pi-hole setup on rasp2 b+ which I use when setting up a temporary network while traveling and sometimes that too has the same symptom, but I quickly resolve that via Upstream DNS Server settings also.
Debug Token:
Hole1 token (the currently non-working setup): ay1b9pgri9
Hole2 token (works at the moment): o7wpnjegh4
Thanks for any suggestions!