I ran a pihole -up this morning and since then I've had repeated interruptions where DNS and the web UI don't work.
The pi-hole is running on bare metal on a Raspberry Pi 3.
I don't think the client device is likely to matter but I've tested primarily on a desktop running Manjaro KDE and a phone running LineageOS.
Expected Behavior:
DNS lookups remain consistently available.
Web interface is consistently available and functional.
Actual Behavior:
Frequent outages during which DNS lookups won't resolve:
$ nslookup example.com
;; communications error to 192.168.2.252#53: timed out
;; communications error to 192.168.2.252#53: timed out
;; communications error to 192.168.2.252#53: timed out
;; no servers could be reached
(192.168.2.252 is the pi-hole.)
During these outages the pi-hole web UI will either not come up at all ("server not found" error) or, if it does come up, will show a completely blank dashboard (the different sections are visible but all show "---" or a Spinning Circle of Death instead of information). There is no interruption in ssh availability; I'm still able to connect to my pi-hole via ssh even when DNS lookups and the web interface aren't working.
I haven't been able to determine a consistent set of factors which precede or follow the outages, and the amount of time they last doesn't seem to be consistent.
Debug Token:
https://tricorder.pi-hole.net/GrSqv7WH/
ETA: A little later in the day and I'm finding the behavior less consistent -- sometimes some domains will resolve and others won't, and sometimes the blank/inaccessible web UI issue will occur even while I'm able to load external websites.
I've added another debug log:
https://tricorder.pi-hole.net/rM58ara1/