iOS Mail App Problems

I use several different apps to access my Xfinity email including Outlook365 on my PC, the Apple mail app on both my iPhone and iPad. I'm having trouble with the iPhone email app. I keep getting:

The Mail server imap.comcast.net is not responding. Verify that you have entered the correct account info in Mail settings.

Also:

Server code "ALERT", server message "Temporarily blacklisted IP Address - try again later"

I thought maybe this was due to my VPN which I have to pause to get to my bank account; however, that worked for awhile, but no longer. I also get the prompt that my imap account password is not correct. That is not the case. The same password is used for the other two devices and I have no problems getting my email. (OX works as well.) I've tried resetting the password in the Mail app but the app insists the password is incorrect.

Can anyone tell me what is going on and how to fix this? I like the iOS Mail app and since I have my phone with me most of the time and because I have my email set up in a particular folder structure, not having that on my iPhone is a real bother.