When configuring Jet Essentials to work with NAV 2013's Web Service, it can be helpful to test the setup to make sure the Web Service is working as expected.
In this MSDN article , Microsoft provides an easy test.
Below is an excerpt from that article.
You publish a web service using the RoleTailored client.
To publish a page as a web service
Open the Microsoft Dynamics NAV Windows client, and then connect to the CRONUS International Ltd. company.
In the Search box, enter Web Services, and then press Return.
In the Web Services page, choose New.
In the Object Type column, select Page, and then enter 21 in the Object ID column and Customer in the Service Name column.
Mark the check box in the Published column.
Choose OK to close the New - Web Services page.
Verifying Web Services Availability
After publishing a web service, verify that the port that web service applications will use to connect to your web service is open. The default port for SOAP-based web services is set to 7047. You can configure this value by using the
Microsoft Dynamics NAV Server Administration Tool
To verify availability of a Microsoft Dynamics NAV web service
Start Windows Internet Explorer.
In the Address field, enter an address of the following type: http://<Server>:<WebServicePort>/<ServerInstance>/WS/<CompanyName>/services.
Note The company name is case-sensitive.
The browser should now show the web service that you have published:
<contractRef xmlns="http://schemas.xmlsoap.org/disco/scl/" ref="http://localhost:7047/DynamicsNAV70/WS/CRONUS International Ltd/Page/Customer"/>