On 2022/01/13 18:05, Leo Unglaub wrote: > Hey, > > On 11/01/2022 21:28, Stuart Henderson wrote: > > I bet it is MTU related. Try lowering MTU on that interface (you > > cannot do it separately for IPv4 and IPv6 so it will change both, > > but that's not likely to be a problem) and get someone who has > > seen the problems to re-test. > > thank you so much for your answer. I would have never ever thought about the > MTU in this case. I used the default 1500. I talked to the technical support > from the datacenter (Hetzner Online) and they asured me that 1500 is > correct. > > However, i have set the value to 1400 and asked some people who had the > issue to re-test it. I will post the results of the test here so other > people can find them via a search engine. > > Thank you so much, very kind of you!
The possible issue is that many people (especially people connecting over tunnels, but also those on pppoe) are on lower MTUs than this. Normally this is OK as fragmentation-needed messages will sort things out but sometimes firewalls are not be configured to pass these which will cause problems. If that _is_ what's happening then there are other ways to fix it but changing MTU is often the easiest one that you can do yourself.
