It has to be a cert issue since I am getting a CORS error now. Going to look into it more and see what I can come up with.
Do you have domains in domains option in config/config.json file?
We try to avoid of using 5443 port, because usually it is system port for servers apps.
Also there are maybe problem with certificate names, if they are updated, names of the cert file maybe changed.
Provide me please with your server's and site details via PM. I will check.