just tried with my phone, tmobile, and I can bring up the site and login ok.
not a great solution but still no go through my ISP.

Do you use your ISP's DNS resolvers? Try changing to better ones like Google's DNS (8.8.8.8 and 8.8.4.4) or OpenDNS. This wouldn't be the first time an ISP's DNS resolvers are giving bad/old IPs for Guild.