If OWA won't load the page and you can't even ping the server, there is a connectivity issue. But, if that's the case your phone shouldn't work either. Are you sure your phone is actually connected?

Another potential culprit is Outlook's HTTP proxy settings. Go into the Mail control panel, edit the settings for your email account, click More Settings, then under the Connection tab click the Exchange Proxy Settings button. Make sure both checkboxes are checked that start with "On fast networks..." and "On slow networks..." It might help.