How to debug a TLSv1.3 protocol problem?

[Claus Assmann]

On Mon, May 18, 2020, Alexander Gryanko wrote:

[thanks for the hints, I will try that ASAP]

> But first of all, check your cert type. Looks like you are using non-RSA
> cert which is not supported by S8.

As I wrote: it works fine if I don't use TLSv1.3 or if I use openssl
s_client with TLSv1.3 (it is an RSA cert and I also tested against
another S8 server which uses a Let's Encrypt cert).