See my other comment (sorry, Voyager seems to generate weird share links).
While violence at schools does exist in Europe, the numbers just don’t compare to the US.
And don’t forget! The US has stabbings too, its just that you have so many shootings that a stabbing won’t make the news.
Also, what are “grooming gangs”?
That page lists attacks in general, and not just at schools but also universities. Out of the 25 attacks listed for Germany (so since 1990), only 11 are shootings, and 14 have no deaths at all. So, you’re right, Germany does know what school schootings are.
But compare this to a total of 67 (damn that number!) in the same timeframe in the UK ( https://en.wikipedia.org/wiki/List_of_school_attacks_in_the_United_Kingdom ), despite the UK containg about 20 million less people than Germany. Unfortunately, Wikipedia doesn’t have a comparable list for France.
But both of those numbers just cannot compare with the US, where just the school shootings that Wikipedia lists (not all attacks, just shootings) add up to 882 over the same time frame. And its not due to higer population, the US only has about 4 times as many people as Germany.
Sorry, I realise you’re kinda just trying to say, school attacks do happen in Germay too, and you’re right. But you sent me down a rabbit hole. And the number of school shootings in Germany is so low that as a parent you can reasonably assume it won’t happen (and they are rarely big enough to land in the news), whereas in the US it seems to be something that everyone thinks about, that schols plan for, and that has a not inconsiderable chance of happening.
Edit: spelling
I’ve never used CasaOS, so I can’t help you with that, but I run NetBird for remote access to my homelab. What you’re describing sounds to me like an issue I used to have with Tailscale.
I think NetBird might be trying to route your traffic through a STUN/TURN server to get around a NAT or firewall. A NAT (in case you haven’t heard of it) is a sort of “mapping” from one IPv4 address to many IPv4 addresses. Its used to "make more "addresses, otherwise we would have run out decades ago. (this is a simplification, its actually much more complicated)
The first thing to check here is: Are you behind a CG-NAT? (there’s probably some websites to check this)
If yes, then there is little you can do without setting up a VPS to get around it.
If that’s not it, then you’ll have to figure out how CasaOS handles networking internally. Your services might be behind a NAT inside.
As for ressources/information, I mostly stuck to the official docs.