Probably not what you’re looking for, but when I had a somewhat unstable internet connection, I’d just self host for myself as much as possible to reduce my reliance on the internet. I ran lancache to cache as many updates I could. I’d download kiwix archives at university and host them at home. I had ripped hundreds of DVDs for Jellyfin and I’d even sometimes record shows off of free to air TV with TVHeadEnd. I also self hosted languagetool (a Grammarly alternative). Although, I still do all that (and probably more) with stable gigabit fibre (except I no longer saw any point in lancache).

An Ethernet frame’s payload can’t exceed 1500 bytes without using jumbo frames. So every internet routable packet is actually less than or equal to 1.5kB.

On that VPS I’ve also installed pihole to act as DNS for the tailnet.

What’s the upstream server for pihole? Is it also Quad9, or are you doing full recursive DNS with unbound or something?

Needless to say, Quad9 is not located in my home country.

Quad9 uses an anycast IP that can route to one of over 200 locations in 90 different nations, usually this routes to your closest location.

You can use on.quad9.net to check if you are using Quad9.