Avoid using /sfdc as a site and community prefix
|Knowledge Article Number||000192832|
|Description||When setting up a communities or a force.com site, if you use the following path for the site: /sfdc, You will notice that the site will only work for requests that originate from the SFDC network. Effectively anyone vising the site who is not on the SFDC network, will be presented with a 404 page is under maintenance page.|
|Resolution||This is intended behavior. /sfdc prefix is reserved for Salesforce diagnostic purposes.
Avoid using /sfdc as your site prefix url and use other relevant prefix to suit your business needs.