Thunderbird client unable to connect to imap.comcast.net

Beginning yesterday, Thunderbird has been unsuccessful connecting to imap.comcast.net to retrieve e-mail.

I have tried other e-mail clients and those have successfully connected using the same server settings:

IMAP: imap.comcast.net, Port 993, SSL

SMTP: smtp.comcast.net, Port 465, SSL

Was a change made to the Comcast mail server that is somehow prohibiting Thunderbird clients from connecting to it?

I have also reinstalled Thunderbird and after attempting to add the e-mail account back in, it has displayed "Checking Password..." with the blue circulating activity indicator for the past 15 minutes. It isn't connecting to the Comcast server to verify the information.