Unfortunately www.keil.com does not appear to have an obvious location to report problems with the website itself. All the feedback/support/contactus assume someone is wanting help with the tool chain products.
When accessing this link to download Keil toolchain free/evaluation version: https://www.keil.com/demo/eval/arm.htm#DOWNLOAD
The following error is display as I am using IPv6. I have xxxx redacted my actual IP network address.
It seems the ASP website can not handle IPv6 addresses in the REMOTE_HOST field but the website itself remains IPv6 enabled and accessible.
Further more it is leaking error information back in the HTTP/500 page that might be useful to an attacker to guess which technology the website is based on, which plugins, code and versions are in use.
HTTP Error 500.100Page Cannot Be Displayed
The page you are looking for cannot be displayed at this time. The webmaster has been notified of this condition and will make any necessary corrections as soon as possible. Typical causes of this error include:
You may try the following:
You will be automatically redirected to the Keil home page in 60 seconds.
cyScape.CountryObj.1 error '80070057'
Error 1123: Invalid IP address "2a02:8010:xxxx:0:608d:xxxx:3f63:2baf, 18.104.22.168". IP must only contain numbers and '.' characters.
/_aspincs/CH_Funcs.asp, line 9