Literally just had my pihole hard crash this weekend due to a bad update to FTL. Apparently they had a major version upgrade and didn't bother to read the notes so I had to do a full OS reinstall.

Back up your configs people. Had to dig through documentation to find the sqlite file and then parse through it like some sort of animal.

I didn't have a problem on my Pi-hole for a very long time too. OP has that probably because s/he's using it as a DHCP server as well.

Right, I didn't have any issues running it on a pi for years too. The problems came when I started messing with things. So, really my advice is to help save people from ideas like mine.

I decided one day to take a bunch of old laptops and create a proxmox cluster out of them. It worked great, but I didn't have a use for them, I was just playing. So, I decided to retire the pi and put the pihole on the cluster. HA for the win!

I did that and came woke up a few days later to my family complaining that they had no internet. I found the pihole container on a different node and it wouldn't start. Turns out with proxmox you need separate storage for HA to work. I had assumed that it would be similar to jboss clustering which I'm familiar with, and the container would be on all the nodes and only one actice at a time, with some syncing between nodes. Nope.

What's worse is the container refused to move back to the origional node AND wouldn't start. The pi was stored away at this point so I figured it would be easier to just create a new container, but duh, no internet. Turn off dns settings on the router, bam have internet.

Eventually set up the old pi again, and it took me a while to figure out what I had done wrong with proxmox. But while I was figuring it out it was nice to have the backup.

Now I always have two running on different hardware, just in case.

I've a single Pihole instance running on a RPi 4 and have experienced not a single instance of any of the 3 probs you mention. Except, of course, the very few minutes it takes for a reboot which I can schedule and am aware when it's happening...

Yeah, I believe it can vary depending on how you host it.

In my experience whenever I brought down the PiHole instance (Docker Compose) I would lose all internet access, which is expected since I’m essentially taking away my devices one and only library, so to mitigate this I spun up PiHole on another device and set that as my secondary (backup) DNS resolver.

This way I can take a container down, update it and all without losing resolution to the internet.

Raspberry Pies (is that how you pluralize it?), and especially their SD cards are not the most reliable pieces of hardware. I've already had a few die on me.

As for how annoying outages are, I guess that depends on how many people and services you have on your network relying on a functioning DNS. I am running two pihole instances on separate hardware in a keepalived virtual IP setup, with a replicated configuration. Sounds complicated, but it's really easy.

It's just nice to be able to reboot or perform maintenance on my pihole knowing it won't impact DNS, and not having to worry about interrupting my girlfriend streaming her Netflix series or whatever. For example, just a couple of weeks ago I converted my bare-metal pihole installation to a dockerized one, which was a couple of hours of work, without any DNS downtime at all.