Thunderbird access to comcast email no longer working

I've just changed my password, and it still doesn't work in Thunderbird. (I've verified that it does still work for webmail.) It still says "Login to server mail.comcast.net with username xxx failed." It always worked until now with mail.comcast.net as the server, but I've also tried pop.comcast.net, which also doesn't work. Everything worked fine last night, but not this morning.

@JeffG4  Please try these steps;

Remove and Re-enter Passwords:

Open Thunderbird and go to Tools > Options (or Preferences on macOS).
Navigate to Security > Passwords > Saved Passwords.
Click on Show Passwords, then find and remove the entries for your Comcast account.
Close and reopen Thunderbird. When prompted, enter your new password.
Verify Server Settings:

Ensure your incoming server is set to mail.comcast.net with port 995 and SSL/TLS encryption.
For the outgoing server, use smtp.comcast.net with port 465 or 587 and SSL/TLS encryption.
Check Authentication Method:

Go to Account Settings > Server Settings and ensure the Authentication method is set to Normal password.
Allow Third-Party Access:

Log in to your Comcast webmail and ensure that third-party access is enabled. This can sometimes be required for email clients like Thunderbird.
If these steps don't resolve the issue, you might want to try removing and re-adding your email account in Thunderbird, then contacting Thunderbird for further assistance. We generally do not troubleshoot third party programs.

I've now tried all that, and tried re-adding my email account, both as POP and IMAP--POP sends me to the Xfinity sign-in page and then errors out, telling me I don't have permission to login. IMAP just errors out locally, saying it is unable to log in at server. So ...

Thanks for your advice, even though this has to do with a third-party email program. I just figured, since Xfinity was doing something new with its email system, this might be a side effect of that.

@JeffG4​ I have the same issue. I can't use Thunderbird anymore with Comcast. Both pop3 and Imap fail. 

I was able to get it working in Outlook with Imap but not pop3. 

I don't know if there was a change in Thunderbird or Comcast.

I had the same issue. It was driving me nuts, but I found the issue. ARE YOU USING A VPN? My Norton VPN was pointing out of the USA. Set it to use United States and everything started working correctly!