Error 400 trying to configure NEST

I’ve been trying to configure NEST for a few days, but after building all configuration twice and checking all tricks on the project page, I’m not able to solve it.

I’m getting a error 400, without any other message that could provide a clue.

I’m not using Nabu Casa. Instead I have my port 8123 is open on my firewall and secured using SSL. Can this cause this issue maybe?