They're getting hugged to death between Reddit and now HN. I had the same thing happen, just waited a minute then refreshed the page and was able to get in.
You significantly overestimate the engineering capability of the telecoms industry. They have very little technical skill in-house, most of the software is written and supported by their equipment suppliers (Ericsson, Huawei, etc) and the customer-facing part were outsourced to the lowest bidder years ago and never maintained again.
This is typical for ATT. I get it all of the time when trying to verify my account for things like HBO Max and other networks' apps. It's very frustrating when you are wanting to watch a live sporting event they are not broadcasting and are only making available via streaming, yet you can't see it because the company that authorizes you can't be reached.
