@willliam The Flic Hub can generally connect to servers that use Let's Encrypt certificates so there must be some other error.
The Wireshark tool cannot be run from within a web browser. You must download the software and run it. I'd appreciate if you could try this. After starting the program, you select "Capture" on your wifi or ethernet interface. Then it starts to log packets. At this time, either run the curl command as instructed in my previous post. Or, if your TLS server runs on the same computer as the one running Wireshark, please try to access the https server using the Flic Hub. Then stop the capture, save, and send me/upload the capture file.