It might not be a routing problem, but if it is this will help diagnose it. I think it might be a DNS (domain name server) issue.
Try the following, and copy and paste the output to a new message.
1) Start | Run | type in "cmd" | Enter (if a black window doesnt come up try "command" instead)
2) type in "tracert www.ar15armory.com
This traces the route your computer takes hop by hop through the internet to get to the destination from your computer.