thunderbird email issue

this has been an issue for years.  see https://forums.xfinity.com/conversations/email/thunderbird-localhost-error/66e9a0adde8d1e3b5f415872 but unfortunately the information there is false.  comcast.net emails do use oath2, have sent up one account in thunderbird with no issue, but it's a secondary on the xfinity account fwiw.  the primary on the account won't set up as it redirects to localhost for some crazy reason per the linked post.  no amount of changing the auth method to other things works either, that just makes it fail instantly without opening the window that tries to talk to xfinity.  pretty dang odd, but hey this form doesn't accept capital letters to be typed so clearly this is a tech company that has a metric ton of tech issues that make no sense...