Not resolving DNS (servfail)

Hi all, I have noticed a strange behaviour for pihole. It works well for some days and then out of nowhere starts responding with servfail to all dns requests. To note: DNSSEC is disabled and it is forwarding to another local dns server after.

https://tricorder.pi-hole.net/y1qm6t7am2

Any help is appreciated!

Have you checked that the date and time are correct on the Pi?

Yup it was correct in UTC. Set the timezone, but that was simply one hour off (UTC+1).
For now I’m trying using Cloudflare https dns and I’ll see how it goes, as well as first forwarding all of the requests to the other local server so that I can have a fallback ready.

Edit: forgot to mention it is running in an ubuntu 18.04 vm.

Chiming back in. After some days of working well (since last posts), now it’s again having troubles.
https://tricorder.pi-hole.net/w9u6089q2m