FYI-
I also have been unable to login to any of the wordpress sites I manage and instead have been getting the 503 error message. 1&1 informed me on the 17th that this is a known problem ‘at their end’ and that they were trying to resolve it. I was informed by the help desk that I would be informed as soon as it had been rectified by email.
The matter does now seem to be resolved in my case; though no notification email has been forth coming. I did have to manually delete the various cookies my chrome browser had stored relating to my wordpress sites before being able to get into the dashboards. Only figured this out by trying to login via a different browser.
