I am able to get a test service running with a self-signed SSL cert and see test messages posted to the server. But when I switch to a CA signed cert generated through let's encrypt, I get an SSL handshake error. Has anyone else had success using a let's encrypt certs with ASK?
Apologies for the late reply, had to look a bit deeper into these Lets Encrypt issues. It seems one of the major problems is that there are two ways to do the certificate chain, and for Alexa to work properly you need to use the IdenTrust signed intermediate, not the ISRG Root X1 certificate.
I've been able to test a skill using letsencrypt and have had no issues since I got the certificate chain issue sorted out. Could you provide more details regarding how you have generated your certificate and the chain you are using?
I couldn't even get my dropwizard services to start up with the LE cert, so I gave up on it, but another user here was having similar trouble not too long ago. I believe their diagnosis was that it was a problem with SNI, and there wasn't really any recourse at this point. Keep us posted if you solve it, though!