Sorry what is the solution?
I have exactly the same issue, I am also an IT and sometimes have to upload large files etc. I had 0.8Mb/s upload which is pretty poor, but then a few of months ago it got worse. Now the measure speed is about 0.45, I thought it might just be temporary, but it hasn't improved. I got here by googling the problem. I've never heard of the 448 cap before, it seems utterly ridiculous to have such a thing. 0.45 by todays standards is a disgrace. I work in Amsterdam and my apartment's internet is 20-40 Mb measured BOTH down AND up. That's on copper btw.
How can I get this improved?