Completely locked out of Webmail - cannot get to sign in page

I am completely locked out of accessing my email via any web browser. I cannot even get to the sign-in page. I have multiple ATT/currently email addresses with the sbcglobal.net subdomain and cannot access any of them. I have had a similar issue before where I have to clear the cache and cookies to completely remove any data relating to one address in order to access a different one, but this is different.

I have already cleared two different browser caches, deleted all cookies, and restarted the computer and am still getting the same error. When I go to the currently home page and click "sign in," I get the "Something's Gone Wrong" message, before I even see the opportunity to sign in. I have seen this error in the past AFTER attempting to sign in to a different account from the one I was just using, but now I am seeing this message after merely clicking "sign in." I never even get the chance to enter an email address and password. I click sign-in and get this message, after the site cycles through 2-3 different URL redirects in the address bar.

I am on a Macbook Pro, this is happening in Firefox, Chrome, and Brave browsers. I have cleared caches and cookies, restarted the browsers, and restarted the computer. The message implies I am not connected... I am connected to wifi. I wouldn't be able to type this on the same computer and submit it if I were not connected. This seems like a major bug that wasn't there before.