Not sure what to say, however if you are in certain regions or countries
outside the USA, Canada, or Europe, there may be some undisclosed
localized internet outages.
The site I just tried shows all of my products by serial number when I'm
logged in, going way back to the first ones I bought from Apple...
https://getsupport.apple.com/
These web addresses may change depending on where you are located.
• Apple - Find Locations - Country Selector:
https://locate.apple.com/country
The global service and support varies by location, region, country, etc.
A country, major city, & address can yield authorized sales, service &
training and/or consulting; availability of these may vary by location.
If you need to know if your Apple device is under warranty and its eligibility for coverage. You
will need to have your apple hardware serial number ready as you will need this information to
check on your device’s warranty. The following apple.com link will take you directly to the main
apple warranty status eligibility page. https://selfsolve.apple.com/agreementWarrantyDynamic.do
You may be able to contact a local Apple authorized service provider in
a region or country wherever you are, if you need service & repair. The
same goes for authorized resellers.
http://www.apple.com/contact/
https://checkrepair.apple.com/
So there may be an outage, or perhaps your internet provider ISP or the
DNS settings for your computer may not be correct to access Apple.
Hard to say at a distance what may be the reason you cannot go there.
• About your support coverage and service options - Apple Support
There may be some other contact info in regional Apple store page online.
Since I've no way to knowing, most of the above is what I found by looking.
And you have not reached an official response in this Apple Discussion post;
instead for the most part, fellow volunteer users will reply and try to offer help.
In any event...
Good luck & happy computing! 🙂