Problem with outgoing mail server for Spectrum

I've spent about 6 hours on 3 chats at Spectrum to fix my outgoing mail server problem on my Mac desktop, without success. I found Spectrum instructions online for setting up Apple Mail. These instructions worked for the incoming mail, but not for the outgoing mail, which is very strange. When the mail used to work, I used mail.twc.com as the server for both incoming and outgoing.

I edit the server list to set the outgoing mail server to: mail.twc.com and click OK. This returns me to the Incoming/Outgoing settings page, where the Outgoing Mail Server account is, "None." When I click on the drop down list and select my outgoing server, it shows the password field empty, and the outgoing server changed to mobile.charter.net. If I set the password and keep the server as mobile.charger.net, it returns me to the Incoming/Outgoing settings page, showing the settings I just made - for a moment - then it shows the account as, "None." I feel like Sisyphus. I don't know what it means when the Outgoing account is changed to "None."