[ubuntu] Cannot sync files on any sync service

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http://ubuntuforums.org – I cannot seem to upload files on any of the sync services. I managed to sync 2MB of files via Ubuntu One, that took 30min, Dropbox and SpiderOak just start and then fizzle out. They show active sync in progress, but there is no actual progress. I use Mobile Broadband USB wireless modem connection on a Compaq Pressario, Ubuntu 12.04. I just measured on speedtest.net, download speed 2.3 Mbps, upload 0.4 Mbps. Not fast, but I used to sync gigabytes of data via Dropbox and Sugarsync on Windows. Right now I cannot even sync 10MB of data via Ubuntu One, after a couple of hours only 6.4 kB synced. (Hardware)