Gmail in Mac Mail stopped working

I've made some progress. By turning off the Mac's firewall I can get past the authentication stage. But what Google installs is an IMAP account, and I've always used POP. I may change that but for now I want my POP account back. In theory I can do that on Google's page for managing such things. That's where I hit another gotcha. Attempts to save the change produce the message "Error. Save settings failed." But that's a problem I'm trying to solve on the Google support pages, so far without luck..

Anyway with the firewall disabled your suggestion works in achieving a workable Gmail account of some sort. Thanks very much!

Thanks for your suggestion AlWeir,

I've actually done steps 1 & 2 but step 2 is the problem. I choose Google (for my Gmail account) and click Continue. After a while I get the message "Authentication Failed. Failed to authenticate with Google, please try again later."

I also went through Gmail's web page, tried changing settings (experimenting with POP, which I use, and IMAP, which I don't, and got a message that saving the changes "failed". I tried this several times and got the same result.

Strangely this morning my Apple Mail app started filling up with old emails, more than 40,000 of them. I have a mere 20,000 in my Google's webmail version, and closer to 30,000 in my iPhone's Mail app. So, not perfect syncing.

And then this morning after opening your email, all Inbox and Sent mail in my Mac Mail app vanished, without me trying to change anything. All that remains is one unsent draft. Webmail is fine, as is iPhone Mail albeit with 50% more mail than in webmail.

All very mysterious.