Software Update Issue - In dire need of NERD power...

Question

Attempted to download Mavericks on my 2011 iMac (currently running on OS X 10.6.6)
App Store returned the following error:
We could not complete your purchase.
OS X can't be installed on Macintosh HD because Mac OS X version 10.6.8 or later is required.
Choose Software Update from the Apple menu to update Mac OS X.
Not a problem, I thought. I chose Software Update from my Apple menu to update Mac OS X and began downloading Mac OS X Update Combined (10.6.8 v1.1) which maintained a good and consistent rate of 10 MB/sec download speed...
...only to hang abruptly at 655 MB of 1.09 GB
Roughly 30 seconds later I receive the following error:
The update "Mac OS X Update Combined" can't be saved.
Software Update can't connect to the update server.
Make sure you're connected to the Internet, and then try again.
To be clear, I'm familiar with issues regarding and related to TCP/IP protocols, firewalls, open/blocked ports, etc.
I made sure that I was connected to the Internet, and then tried again.
The download progress stays put at 655 MB of 1.09 GB, then returns same error.
At which point I decided it might be a good idea to delete the partially complete download and start over. An Apple Support article directs me to /Library/Updates where the partially complete package parts are temporarily stored and I move them to the Trash.
Every single time I try starting the download over (due to what I suspected might be an connectivity issue that I somehow missed) it always went the same:
Download starts, coasts as 10 MB/sec, hangs at 655 MB of 1.09 GB, and returns the same error.
I thought it was odd that it would always hang at the exact same spot so I checked the /Library/Updates folder while the download was active. The package is downloaded in parts and it would always freeze after completing part10. For testing purposes, I duplicated the part10 file and renamed it as "part11" to see if the installer would recognize the dummy part--AND IT DOES! The download happily chugs past 655 MB and continues to write part12. Obviously, this did not solve my problem because once the download finished it could not compile the parts due to the real part11 being missing. It did, however, at least reveal what the problem was: the server could not retrieve that one specific file, part11.
Sadly, I'm at a loss as to where to go from here. As far as I can tell, it doesn't seem to be a connectivity issue on my end--if anything, Apple servers are the one with the issue--maybe a corrupted file? All I know is that I've pretty much exhausted all the options in my head and this is my last resort: posting on the Apple Support Communities (not that there's anything wrong with posting here, I just don't expect a genius to pop out of nowhere with a solution in hand).
p.s. my apologies for the lengthy post, I was trying to be as thorough as I could in order to alleviate as much back and forth one-line question and answer posts to save everyone some time :b

Answer 1

Yeah, I actually tried going the manual way not too long after my original post and unsurprisingly, the download would go smoothly only to halt at a certain point again. In fact, I tried downloading not only the MacOSXUpdCombo10.6.8 but also MacOSXUpd10.6.8 just to give it a try and that too halted during download.
The most perplexing part is that these download errors exhibited the EXACT same issue of halting at a very specific point. To be doubly sure, I tried downloading multiple copies of the same file at different times with some overlap during the download times (basically started two downloads of the same copy a few mins apart and I got these results.
try#3 - MacOSXUpdCombo10.6.8 - stuck at 232 MB of 1.01 GB (kept open in Download window for reference)
try#3 - MacOSXUpd10.6.8 - stuck at 430 of 454 MB (kept open in Downloads window for reference)
try#4 - MacOSXUpdCombo10.6.8 - stuck at 232 MB of 1.01 GB
try#4 - MacOSXUpd10.6.8 - stuck at 430 of 454 MB
try#5 - MacOSXUpdCombo10.6.8 - currently chugging at 61.9 of 1.10 GB, but i'm pretty sure when it's going to stop...
Come to think of it, whenever I tried to update games like "League of Legends", or download/update a Steam game I always get stuck at 33% or 99% respectively. Most recently, I bought "FFXIV:ARR" as a digital download and I haven't been able to get past a very specific point in progression for the game client download as well. So in contrary to my first assessment, it most likely IS a problem on my own end but these "symptoms" seem very clear and specific, I just can't pinpoint the problem. I don't have "connection time-out" problems when doing downloads on my work network, only at the guest house where they assign me a TCP/IP configuration for internet connectivity (which also severely hampers my ability to troubleshoot). On the other hand, P2P is just fine but I suspect that's because it doesn't require a contiguous download.
TL;DR
Large downloads/updates over one specific network (assigned TCP/IP) always hang at specific point in download completion. Internet connectivity for browsing is fine, P2P downloads are fine.