I'm working on this for about 5 hours and I still couldn't find a way to not send the emails of my private server to the spam folder of gmail.
The error I'm receiving in google is:
Received-SPF: neutral (google.com: 212.113.177.3 is neither permitted nor denied by domain of [email protected]) client-ip=212.113.177.3;
Authentication-Results: mx.google.com;
spf=neutral (google.com: 212.113.177.3 is neither permitted nor denied by domain of [email protected]) [email protected]
I actually do not know what d'hell is the IP 212.113.177.3, but a search around the google told me to add some SPF to my domain, so I did.

But the emails continue to go to the SPAM folder. So I went to the SPF Record Checker and they output the following results:

What am I doing wrong in the SPF?