Are you able to refresh the extract from Tableau Desktop without issue? If so, are you able to try refreshing the extract from Tableau Desktop on the same computer as Tableau Server?
For Tableau Server to connect to a Flat file data source (like MS Access) on a remote share, there are 2 main requirements
1. The path to the File needs to be in UNC format. This means not connecting to it via Tableau Desktop using a driver letter, such as X:\folder\database.mdb, but connecting via \\servername\share\folder\database.mdb
This sounds like it has been done as you say you are connecting via IP address.
2. The RUN AS account that Tableau Server is running under needs to have permissions to this file and folder.
Generally this is done by using a Windows Domain account, and permissioning that account against that folder, and giving it Read Access. This can be (should be) done via being a member of a group.
A potential third issue is that your Tableau Server is Firewalled off, so that it cant access the share. In which case the correct ports need to opened to gain access. A discussion with your Networking Team is needed for this.
A good test is to login to the Tableau Server (using RDP) as the RUN AS account, and using File Explorer see if you can access the MS Access DB.
Also, (as Diego has said) attempting to connect using Tableau Desktop on the server (under the RUN AS account credentials) will also test connectivity
Hope this helps