"Access to resource forbidden" for sync export to excel on own Kobo instance

Hi all, for various legal reasons we have been required to deploy Kobo on a separate server instance. We have installed the most recent updates.
We are collecting data in two separate forms and using synchronous export to download them into Excel. All these steps have been developed and verified as working on https://kf.kobotoolbox.org/
Now however, as we are migrating to our own server, we are no longer able to export the data.
Using the same steps as normal in Excel (Global Permissions >> Clear All Permissions, then Get Data >> From Web >> paste the url and select Basic >> input user credentials) we get “Access to Resource Forbidden”.
The login credentials have been confirmed as working. The only difference I can see is that we have turned on 2FA for all users.
Any assistance with this issue would be much appreciated.
Best Regards