It adds a bit of latency (and is definitely not the best solution in
theory), but finally allows dropping IPv6 NAT and it works within the
constraits my home network has to live in.
The old provider was doing weird stuff with DNS that I wasn’t able to
debug well.
However, apparently, the old provider did MSS clamping on their side.
Therefore, it is now required that I do this on my side.
Simon Bruder