It looks to me like the DNS (Domain Name System) is where the trouble is - this is the part of the internet that changes a host name such as www.cmcmarketsstockbroking into an IP address like 123.112.12.230. It may be that a site that happens to host the DNS records for a bunch of Aussie financial instos is down, rather than the instos internet connection themselves. This may be why a single failure is affecting access to multiple businesses.