Hi all, I have the same issue. Searching for an error I see this post but not answer.
In a couple of standalone installations I can't log on into the administration console. The gateway works fine, but when I open Firefox inside the Zentyal with the address
https://127.0.0.1 or localhost I have not response and I can't enter the console.
Rarely if I try to enter the Captive portal in port 4443 I have access through web inside the Zentyal.
Because of this error I have to reinstall all from scratch but I can't do it everytime this error shows up, and it's happening in different installations with different hardware config.
Regards!
(forgive my english)