How to manage Oracle APEX XE http access
This page controls local and remote HTTP access to the APEX user interface.
By selecting Available only from local server, only HTTP requests that originate from the same physical server where the database is installed are able to access this user interface. This is the default setting.
By selecting Available to remote clients, HTTP access to this interface is enabled for all clients on your network that have a browser.
If you have upgraded XE to V3 then you need to perform step 5 as shown in the XE upgrade process.