SSL certificate issues
Sites can be checked here for issues: https://www.ssllabs.com/ssltest/analyze.html
An example of a certificate issue is when "chained certificates" are not provided by the server. The web page may work in a web browser on Windows or MacOS but not on LG or Samsung screens.
This is because these browser and OS come with a set of root and ca certificates which do not exist for the LG WebOS or Samsung SSSP.
The solution is to make sure that the web server sends the whole chain. The site https://whatsmychaincert.com/ can assist with that.