Error: "Unable to Connect" Oracle Apex Access Issue

Recently we had install the Oracle Apex and installation done successfully and access via local system Oracle Apex running perfectly but while we access in remote then we had faced the problem in Oracle Apex Application running issue.

Error: Unable to Connect

Cause: APEX using the XDB protocol if you use XDB protocols and then need DISPATCHERS but we had not configure the dispatcher.

Solution: One thing to remember, if you are only using XDB services for batch processing or only for intermittent connections you can actually set DISPATCHERS dynamically and turn it on.

This is because XDB protocols like HTTP and FTP require shared server. 

Example: 

dispatchers="(PROTOCOL=TCP)(SERVICE=TESTXDB)"

LOCAL_LISTENER = "(ADDRESS=(PROTOCOL=TCP)(HOST=Hostname)(port=1528))"