Email "server unreachable" message pops up

I am also having problems connecting with the Comcast mail servers, whether I use my dedicated email program or whether I use the Comcast web-mail portal (Xfinity Connect).  My email program often takes a long time successfully completing the handshaking with the Comcast server..  The program displays a "Connecting to the server..." message for many minutes, and then finally the handshaking process completes and typically several messages appear in my email program's In box.  When I try to use the web-browser-based Xfinity Connect, <https://connect.xfinity.com/appsuite/#!!&app=io.ox/mail&folder=default0/INBOX>, the progress wheel with two arrowheads (to the right of the Compose link) cranks and cranks, with no evident progress.  Eventually, a connection is made, and I can then see any new messages that have arrived at the Comcast mail server.

I encounter similar delays when I try to send messages.

It all seems hit-or-miss.  I have detected no noticeable pattern.

I believe that this started happening two or three days ago.  I have made no changes at this end other than to restart my modem and to restart my computer.  

Restarting my modem has had no noticeable effect (not that I thought that it would).  Restarting my computer likewise has had no discernible effect.

I did see this message about an expired Security Certificate:

<https://forums.xfinity.com/t5/Email-Web-Browsing/Xfinity-needs-to-update-expired-SSL-Certificates-associated/m-p/3360412>

I wonder if that has anything to do with it.

I had the same issue months ago.  I reported it to Comcast under a support ticket and talked to two different techs, neither of whom were helpful.  After a couple of weeks, it stopped occurring.

About 3 or 4 days ago, it started again - the orange popup at the bottom of the Xfinity Connect page that says SERVER UNREACHABLE.  I'm thinking of calling support under the old ticket number but know it won't get me anywhere.

This only occurs on one of the computers in my house and it is a wired connection so it's not a wi-fi issue.  Hoping someone will see these posts and comment.

Reinstall widows by using the overlay method. I got the file from windows and it fixed it.