On Wed, May 20, 2020, Matt Caswell wrote: > I wonder if there could be some middlebox in between these two peers > that is interfering with the connection in some way and arbitrarily > closing it down? No, it's being tested on localhost. And it works fine if I use a different server (e.g., openssl s_server) or a different client, i.e., it is (so far) only this specific combination (M1 -> S8) which does not work.