Could not load view: DataProxy returned an error (Data transformation failed. HTTPError: HTTP Error 404: Not Found)

I am running CKAN 2.9.2 on Ubuntu 20 for a productive instance with https. I am having recently several problems like this one:

```
Could not load view: DataProxy returned an error (Data transformation failed. HTTPError: HTTP Error 404: Not Found)
```
when I try to have a csv file visualized in the Data Explorer. This is for a private dataset.

I assume I have to change the options `ckan.datapusher.url` and/or `ckan.datapusher.callback_url_base` in the configuration file but I don't know exactly how.
I currently have `ckan.datapusher.url = http://127.0.0.1:8800/` but I guess this cannot work when you have an instance with a registered domain.

Could I get help with this? I know that I can make it work by making the dataset public, but I would be more interested in having it working for private datasets.