Hi,
I know hat there were already a couple of questions about this topic and I tried to find a solution within those posts, but unfortunately I was not able too.
I am using a self signed Cert on my server (ver. 13.0.1) and I am trying to connect with the windows 2.3.3. version to it. I am running several other clients on Android, IoS and MAC and do not have any issues with them. The windows client does let me add an exception to use my cert.
So I read the advice to use let’s encrypt, which I would not have an issue with, except that I don’t have a domain and I don’t need one. I am certainly capable of remembering a few digits 
Please correct me, if I am wrong here … I am for sure no expert on this topic.
So, if anyone has a hint for me, that would be very much appreciated.
Thanks
Chris