I updated the firmware from os3 to os5 5.12.108, and when I try to access the dashboard through https it does not work.
What I tried to do, and did not work:
Toggle the https redirect on and off
Restore system to defaults
A port scan does not show that the https port open.
If you disable HTTPS Redirect in the Admin UI, you can still use HTTPS but you’ll get the browser security warning because the browser cannot verify the cert for the internal IP address.
https://IP_ADDRESS:8543
The article below has the explanation for the HTTPS error when the redirect is not used.