Hello:
First post here, specifically to respond to this thread.
I have been using Outlook 2019 with POP Gmail configured for over a year without issue. Beginning 7/18/22 my Gmail account will not connect to pop.gmail.com through Outlook, triggering send/receive error 0x800CCC0F: The connection to the server was interrupted. If I remove the account and attempt to recreate it, Outlook reports 'The connection to the incoming (POP) or (IMAP) server was dropped.'
Google retired their 'less secure devices' option back on May 30th, and POP/IMAP connections now require OAuth 2.0 (OAuth2). My Google account has been using 2-Factor Authentication since long before then, and my pop.gmail.com account configured within Outlook has used an app password for over a year. Unfortunately, neither Outlook 2016 nor Outlook 2019 support this security protocol. From what I have read, neither does Outlook 2021.
I even generated new app passwords to help troubleshoot, but the connection continues to drop with Outlook before it ever actually authenticates my account. Meanwhile, Mozilla Thunderbird works fine as it has OAuth2 as an option in the account setup, but is not a preferred replacement.