Webdav & MS Access multi user

I use Netdrive’s webdav on three computers. I have an Access database which is splitted in a front- and back-end.
The back-end is located on my Synology diskstation, which is accessible trough webdav.
The problem.
When I make a change on PC1 I cannot see it on PC2 and vice versa.
The backend seems to be in a cache after both pc’s have connected it.
When I make the connections without Netdrive by assigning the path to a driveletter it works perfect: every change is immediately visible on the other computer.
But, i want to have this function too when I am not at home and work via internet.
Is there a cache and how do I switch it off.
Background upload is switched off and I think upload-on-the-fly has no influence on this.

Hello Willem

Thank you for using NetDrive.

As you know, NetDrive has a cache for performace.

Unfortunately, there is no option to turn it off.

We will consider adding the features you want.