I guess network admin can sometime limit the throughput on the network side... :)  An entry was made awhile back on the firewall to limit the download/upload limit for an IP that was being assigned to the server by the DHCP server... And that it why my download speed was so slow.    
Hi, I'm running into an issue on the PE R620 and hopefully someone can provide an answer here.  I installed Windows 2012 R2 on R620 and when I was doing the Windows Update I noticed that it is really slow. After looking at the throughput, I noticed that the it is downloading at 20 kbps and that did not make any sense. So I unplugged the Ethernet cable from NIC1 and connected to NIC2. Of course, the download process started at normal speed.  I then plugged the Ethernet cable back to NIC1 and visit Dell website to download a firmware and I noticed that it was behaving the same.  Next, I decided to update both the Windows driver and the board firmware to the latest version (available on Dell). The update was successful but that did not resolve the issue. Also, Bios, Lifecycle controller and RAID controller were all updated to the latest version. I then run Dell pre-boot system assessment and every single test passed. With that, I decided to order a new Intel I350. Got the board today, installed it and it is behaving the same. I re-installed the OS.. still the same thing.  Also, I came across few posts that talked about disabling "Large Send Offload V2" which I did, and rebooted the server. That did not help.  And finally, I took a different approach and booted the server using Ubuntu Live CD. and it worked OK... I managed to download files at 5 mbps.  So what can cause this? Why throughput on NIC1 does not exceed 20 kbps?  Thanks. 
R620 - Intel I350 NIC 1 slower than the other three