Multiple upload errors when trying to fill multiple libraries from windows

When I’m trying to fill 20 synced but initially empty libraries in windows I get stuck as soon as I start the seafile client. I copied around 35 Gb of files into the folders and now I want to sync them back to the server.

Some libraries are synced are many just show an upload error. Some say connection interrupt while others just upload normally.

I guess this is some sort of upload limit parameter problem but I have no clue where to look.
Can someone tell me how to fix this? Seafile Server is Version: 6.3.7. Windows Client is the latest version.
We use Ubuntu as suggested and Apache.

Please check the sync client’s logs. Right click on the systray icon and click on “log folder”