I too spent a lot of time with Kobo Help via Chat. Their conclusion was that it was either an ISP problem or a computer issue on my end, even though I told them it was multiple browsers, etc.
However, as of 10 minutes ago, the Kobo website came back up with a new site address. It's changed from
https://www.kobo.com to
https://www.kobo.com/us/en.