Error The provided login data to access mail server imap.comcast.net seem to be wrong. Please correct them.

"The entered credential or authentication information does not work or are no longer accepted by provider. Please change them."

Secondary comcast email account, been working fine for 10 years.  Stopped working - could not access via signing in to Xfinity on line directly.  Or from iPhone, or from Outlook.

Tried to change incoming server password - assume that password is the secondary account password.  Is it?

I need help figuring out what to do to get this corrected.  I need the email content accessible.