Parallel Upload - Nextcloud client

Hi there!

I’m trying to increase the number of parallel connections from my desktop client to my nextcloud server to speed up the upload (about 250GB of data to upload and counting…).
From my understanding, this is possible by changing the environment variable OWNCLOUD_MAX_PARALLEL to set the max number of connections/jobs for the client.
This does not seem to have any impact in my case as the number of connections between my server and my client never goes above the default max value of 6 (checked by running netstat on the server).

Did anyone ever confirmed that this config parameter was functional? What am I getting wrong?

System Specs: Nextcloud server 15.0.2 - Nextcloud client 2.5.1

Thanks!
Mickael