Hi George, what address do you use to check your email? When I go to the Xfinity site and click the account icon, I see this link below the login fields:

Check Email: https://xfinityconnect.email.comcast.net/

Another user mentioned getting this error message, and then discovering another way through a new Xfinity page -- I think it's: https://www.xfinity.com/hub/

... the first tab that had come up is new weird "Discovery" page as new way to sign in to Xfinity/Comcast which I've never used yet but there is a spot to click on for emails so I did & my email page came right up.

I've tried both links you suggested. I continue to get the same error PR_CONNECT_RESET_ERROR.

Not sure why this is happening only in Firefox and only with the xfinity websites.

I'm not sure either.

Is the problem in accessing any Xfinity address, or after you submit the login form?

Any difference if you try accessing the site in a private window (Ctrl+Shift+P)?

More info . . .

The error happens as soon as I try to reach the login page from https://www.xfinity.com/overview by clicking "Sign In" in the top right corner. The screen then shows the error. So I don't even have the chance to enter my login credentials.

I tried going accessing from a private window -- it worked fine! The attached image is what appears when I click the "Sign In" from a private window. No problem!

So now what could be the problem? Thanks!

I think when you use the Sign In button, the site navigates to https://login.xfinity.com/login but I'm just testing here and there and don't have much experience with it. Is that the server where you get the connection error? Someone else posted a screenshot where it was a server name starting with oauth (which is odd, unless someone signs in to Xfinity using a Google account or other third party account).

It's great to know a private window is an option, but in a way, it adds to the mystery. The most obvious differences between regular and private windows are:

(1) Files in the regular web content cache are not used for private windows

You mentioned that you already cleared the cache (How to clear the Firefox cache).

(2) Cookies set in regular windows are not used for private windows

To clear Xfinity cookies, you can use the "Manage Data" button on the Settings page. That dialog should list all the variations of xfinity.com for which Firefox has stored cookies and you can remove those without affecting other sites. (See the "Clear cookies for any website" section of Clear cookies and site data in Firefox)

(3) Some extensions might not be running in private windows

Among your add-ons, extensions need to be expressly allowed to run in private windows, so possibly one that is active only in your regular windows is causing a problem. You could take a quick look on the Add-ons page. Either:

• Ctrl+Shift+a (Mac: Command+Shift+a)
• "3-bar" menu button (or Tools menu) > Add-ons
• type or paste about:addons in the address bar and press Enter/Return

In the left column of the Add-ons page, click Extensions. On the right side, find the "Manage Your Extensions" heading.

On the "Enabled" list, the ones with a purple mask icon are allowed to run in private windows, and the ones without can only run in regular windows. Nor sure whether there are any of those that could be modifying your requests to Xfinity (for example, changing request headers, cookies, browser identification, etc.).

Problem is solved. I had previously tried clearing the cache and disabling all the add-ons. That didn't work. Deleting the cookies related to xfinity and comcast solved the problem.

So thanks for the suggestion of trying to log in using a private window. I didn't think of that. That led us to the source of the problem.