iPhone email client

Saturday, I was no longer able to send or receive Comcast emails on my IPhone email app. I’ve tried all of the suggestions short of deleting the Comcast account and installing it again. My Gmail works fine on the same app, and I can send and receive Comcast emails on the Xfinity app, although that’s not a satisfactory solution. When I try to send emails on the IOS mail app, I get a pop up that my Comcast username or password are incorrect. I know this isn’t correct because I logged into the email client on my newest Kindle using the same username and password and the mail set up instantly. I don’t want to delete and reload the Comcast email on my account because if those carefully organized mailboxes and emails were lost they would be irreplaceable. While I do have a VPN, I have paused it and it still rejects me. Help please.