Email connection question

Windows 10 Home (X64) Version 1703
I have used comcast.net server and Windows Live Mail for years. Just recently WLM stopped making a connection and delivered an error report. I had a chat with a Comcast agent and reviewed all my settings but no improvement. Thinking that WLM is now passé, I tried a slew of other clients including Opera Mail, Thunderbird, EmClient, Mailbird, Outlook, OE Classic. Only one, Mailbird, works, so I'm using it. But It is a bit underpowered so I'm still looking.

Yesterday evening I turned on WLM and, voilà, there was new mail. I slept comfortably and tried again this morning. Nope, back to the error report.

So one possibility is that there is something flaky about my system. At last, my question: How can I check and possibly repair the network access on the system?

What is the error message is this imap or pop?

Thanks for your response.

Unable to send or receive messages for the Comcast (xxxxxx) account. Your server has unexpectedly terminated the connection. Possible causes for this include server problems, network problems, or a long period of inactivity.Server: 'mail.comcast.net'Windows Live Mail Error ID: 0x800CCC0FProtocol: POP3Port: 995Secure(SSL): Yes

I actually have 2 accounts. Both respond the same.

BUT

When I just started up WLM to try this, all my incoming mail was there in the inbox waiting for me! Just like yesterday. So it is working but not responding to get and send commands. Can't tell if the less used url is working, I'll have to send a test message. The connection is POP and does require security. I don't know whether I can send mail from this client. Probably have to wait for the mystery connection. I did try IMAP without success.

A little later: The test message was sent but I'll have to wait to see if it appears.

I think it's solved. I called comcast and they referred me to MS Office Help for Outlook. The agent connected to my desktop and fiddled with Outlook quite a lot until, magically, it worked. This took about an hour. I carefully saved all the parameters but I don't know exactly what she did to kick it. Everything I ever said about MS is hereby recanted. Total time: 2 hours. As a bonus, the modifications also helped WLM and other clients.