The only option left to the desperate Gmail user who needs to fix the mail server imap Gmail com is not responding error to his or her Gmail account. You need to know possible reasons to solve this error, check this below: -
It may be mail client error
Remove and Re-Add the Email Account
It may be wrong SSL Settings
You can fix above reasons that will be useful.
Read more - https://emailscrunch.mypixieset.com/blog/fix-imap-gmailcom-is-not-responding-to-iphone/