imap.comcast.net is not responding

The server is failing to communicate with three email clients on three devices. Secondly, the server does not respond to pings. Login to the web portal is functional. The clients have the correct password. The clients are setup with the following. 

Incoming Mail (IMAP) Server

• Server - imap.comcast.net
• Port - 993
• Requires SSL - Yes

Outgoing Mail (SMTP) Server

• Server - smtp.comcast.net
• Port - 587
• Requires SSL - Yes
• Requires authentication - Yes