Incoming POP3 Mail Stopped Working

We get e-mail from 3 different Comcast accounts in Outlook 2016 via a POP3 mail server.  They have worked fine for years, but suddenly stopped working Monday (15 Mar 2021).  The last e-mail I have is time stamped at 17:00 MST that day, and I've had no incoming e-mail for over 24 hours.  Did the POP3 Incoming Server settings change?  Has POP3 been discontinued?  Outgoing mail works fine.

-Kent