Login to Outlook from Gmail with POP3

I received notification that my Google Account was unable to check messages in my outlook.com business account (custom domain). So I checked that the 1.4.2021 address of the POP3 server is changed from pop-mail.outlook.com to outlook.office365.com. I changed and try again but I still received an error:

There was a problem while connecting to outlook.office365.com

Why my SMTP account was working still when the password is not matching? Then Gmail offers only explicit SSL connections, but Outlook is mentioning TLS. Well, it doesn't matter, Google knows both.

I tried to change to better protocol IMAP, but Gmailify was unable to recognize the outlook on a custom domain. What now? I went to outlook settings and changed my password and voilà Gmail accepted the connection to Outlook. (I added also the Autentificator app since my phone number was colliding with my private account too)

Simple answer: disconnect POP3 + SMTP from Gmail. Change Outlook password and add it again to Gmail. I hope it helped.