Old browsers speak HTTP 1.0, which adhered to the old "one service per IP" rule. This doesn't work so well with cloud based stuff, or shared web hosting.

HTTP 1.1 added the `Host:` header, which let a single IP host many domains, which essentially created the web hosting industry.

You can fix this communication problem with a HTTP 1.1 to 1.0 translating proxy server: http://www.jwz.org/blog/2008/03/happy-run-some-old-web-brows...