I run https://podnews.net through AWS, and use their SNI SSL certificates. This appears to work fine for everyone.
For the newsletter software, my click throughs go through https://sendy.amazinglybrilliant.com.au which is a Lets Encrypt certificate running on an Amazon EC2 instance. Some people (perhaps 5%) complain that none of these links work.
I've tried looking at both these sites through an SSL checker, but can't see any obvious reason why the Amazon one would work, but the LetsEncrypt one wouldn't.
One user is using Chrome on a Mac, through a corporate internet connection. The error message he gets is ERR_CONNECTION_RESET
What should I be looking for here? I'm confused why they both work differently; SNI issues should cause both to fail.