Does the free version support multipart uploads?
Just to confirm, you are saying you have 4.8 Mbit Upstream connection speed, resulting in upload speeds of 600 KB / Sec. I'd estimate you're looking at a minimum of 4 hour+ upload time for that file at that speed, assuming you're able to use all available bandwidth.
Can I ask why you're using Glacier Direct as your target? Is this simply for archival reasons. Meaning, you do not have any plans to access that data unless something critical happens and you're also planning on leaving it in Glacier for at least 90 Days to avoid early deletion fees?
Upload issues can be caused anywhere in the chain. It's impossible to guess what's going on. What are your Chunk Settings? There's a section in Options called Glacier Multi-Part Upload.
You can have a look at the Log to see if anything interesting is being reported regarding the transfer to Glacier. Look at the Diagnostic and Logging section in Options. Feel free to post any log items that are of concern. Please do not attach the entire log file as they contain information that you may not want public.