Restore - download background

[orgChris]

Case number 07703793.
Is there a maximum download speed for zip files created as part of a background download job? I'm getting 300 - 400 kb/s on a good stable 1Gb connection.
And the disconnect / Are you still there? pop-up message interrupts the ongoing download.
And if the session disconnects, the partly downloaded file cannot be found and I have to start the download from scratch.
The documentation mentions large .pst files are split into 10Gb chunks, but that does not seem to be the case for SharePoint / Teams / Onedrive data.
With the current settings it seems unlikely that we can restore - background download 30Gb of data. Most organizations will have large amounts of data. What are our options?