Where do I set ports in Mail for incoming and outgoing mail server access?

I had an account in Mail for another provider (Spectrum/Charter). I have been unable to connect to charter since Nov. 5th. They told me it was an Apple problem but I was able to set up an account through another mail server and connect, so it is a charter/spectrum problem. I spoke to a tech rep and tried to make the changes, but that wasn't working, so I deleted the Spectrum/Charter account opting to start over. Now when I try and create the new account through mail>add account, because I can't add the ports in during the "add account" portion of adding a new account, it won't connect and create the new account. I need to add the ports when I set up the new account or it won't connect to the mail server. It use to be possible when you set up a new account in Mail to specify the ports, account type (POP, IMAP), SSL, Password, etc all before actually trying to connect to the server. Now in OS Sierra, I am only allowed to specify the Name (Email), User Name, Password, Connection type, but once I get to the Account type/Incoming and Outgoing Mail Servers, I am not allowed to specify ports and therefore connect to the server I want to verify and establish the email account. I do have all the information I need to set up the new account, but unless I can enter the ports so the connection can be made, I can't establish the account.

I am trying to establish a new account. The account will not authorize access to the mail server until I set the ports. The ports can't be set until I have the account. When I try and establish the new account, I get the spinning wheel and connection does not occur so the account setup can't be completed. Is there a way to set up the account without getting authorization from the server so I can go in and edit the ports and then try and establish a connection?