Since you can get to speedtest.net I doubt the nic is dead on the upload side.
Try a different internet speed test......use google.
These test seem to use flash player.......got the latest?
I have a 10/100/1000 Intel NIC that is having upload issue. I went to speedtest.net and the download would be fine but when it's testing for upload speed, it failed.
Any suggestion how to to resolve or troubleshoot this problem is much appreciated.