Wow, this may take awhile for me to absorb and accomplish.

As a main frame programmer/analyst I rile at the half-baked products being produced for PCs and with their lack of explanatory user guides, etc. People expect too much of the skill and knowledge of others so things are almost always left out of scripts given over to those needing help. While well meaning, it fraustrates the helpee no end.

This is not to imply that this post is in that category, it is just something I have been concerned with for a few years. 
It (this post) certainly is complete and is expected to be of great help is chasing this problem.

Here are some comments in answer to questions or statements in your post:
  
  - I did view and follow the content of the Comcast file you mentioned. In fact I have gone back and reposted everything called for endless times, to no avail. I have run the 'test' contained in the Outlook setup at Tools\E-mail accounts... more times than I can count. I cannot see where my entries vary from what is called for in the file.

  - The 'connection to server' test is something I am eager to do. Because the setup test error msg mostly indicates a problem finding a server.

  - I have only used one modem (DOCSIS 3.0) recently.

  - I have avoided putting a ROUTER into use due to my lack of knowledge about configuring it for security purposes. It seems to be the opinion of the skilled that adding a router without fully setting several security features is tantamount to insanity.

  - Regarding multiple email-capable devices receiving incoming mail. I don't follow what you said about this. Actively calling for incoming mail to be downloaded is not something I have ever had to do. If my email app. was closed when mail arrives at the server, it is saved and then forwarded to my inbox when the app. is activated. Likewise, if the app. is active when incoming mail arrives, it flows right into the inbox, automatically. Incidently, I have selected to have a copy retained at the server, both for my Office Outlook and my Outlook Express email apps. Finally, as I said in one of my posts above, the day I was preparing to provide answers to one of the earlier post, I started up Office Outlook on my new PC and was walking through the setup process in order to see the names of the various setup screens and some of the names of boxes requiring entry. This required me to go in sequence through the screens clicking the OK button at the bottom of each screen, effectively, 'entering'  all the called for text and option selections just as if I was doing it the first time. When I clicked Finish, lo and behold, the Outlook inbox filled up with about 8 emails that arrived that day and a day or two earlier. I thought, gad, finally, this thing is working. But, it wasn't to be. When I went back later that day and reopened Outlook (I had closed it out earlier), it was back to not working and not receiving incoming mail.

I thank you for your post and I will be walking through it very soon.