We have recently installed Windows Server 2012 R2 in our school.

I noticed, that bandwidth to one client is somehow limited to around 30mbps.

This server is gateway to internet.

When we had UNIX box, no problems occurred regarding speed.

AD is not set to limit bandwidth, as it was everything fine, when UNIX box was in place.

What could be the culprit? Tried various hints, such as https://www.duckware.com/blog/how-windows-is-killing-internet-download-speeds/index.html , but none seems to work.

We have: Gateway - Windows Server 2012 R2 (Routing, DHCP, WSUS, Firewall) (WAN IP) DC - Windows Server 2008 R2 (Apache, MySQL, FTP) (SpeedTest Mini) (LAN IP) Client - Windows 10 (x.x.4.1) firewall rules, to redirect WAN IP to some ports, including 80 to LAN IP

Scenario 1: Client runs speedtest on WAN IP - speed around 30mbps.

Scenario 2: Client runs speedtest on LAN IP - speed hopping nearly 100mbps

Scenario 3: DC runs speedtest on WAN IP - speed around 30mbps Basically it runs speedtest to itself, but through gateway

Scenario 4: DC runs speedtest on LAN IP - speed around 200-300mbps - still, it is internal traffic, in same box

Scenario 5: Gateway runs speedtest on LAN IP - Download speed hopping nearly 100mbps, Upload around 22mbps

Scenario 6: Client runs speedtest on WAN IP - Download speed hopping nearly 100mbps, Upload around 22mbps

Scenario 7: Gateway copies file to Client - around 100mbps

Scenario 8: Gateway copies file from DC - around 30mbps

EDIT Scenario 9: 3 Clients runs speedtest, all get 30mbps. It seems, that it is limited per client, but as I said, this was not an issue with UNIX box

EDIT 2: Scenario 10: Client copies files from DC via local share (LAN IP) - around 100mbps

  • When you had a UNIX machine as the gateway, what speeds did you see? Are you concerned about the internet speed or the LAN speed? Is this a gigabit LAN? What speeds are you expecting from your ISP on the internet side of things? – Tedwin Apr 19 '16 at 15:59
  • UNIX box were not limiting it in any way, regardless of what our ISP gives. We expected around 80mbps, but discovered, that we get full 100mbps. We are concerned of LAN speed when accessing it via WAN IP. And speed to internet via WAN. – Žygimantas Markevičius Apr 19 '16 at 16:04
  • I'm sorry, but all your scenarios are confusing. I don't really understand specifically what you need help with at this point. – Tedwin Apr 19 '16 at 19:41
  • Results are also confusing us. When client browses internet, download some files, or torrent, traffic seems to be capped around 30mbps. We do not want bandwidth to be capped. Yes, we may want it later, but we could do this with GPO. This speed limit affects all devices, that are browsing wan. Confusing is, that, DC is making internal speedtest via WAN IP, it gets capped also. We want to eliminate speed limits. – Žygimantas Markevičius Apr 19 '16 at 20:51

It appears that two of our NICs were faulty, one would give 100/30, other - 30/100. Third one was older but working perfectly. Still, we ended up buying Intel card for future reliability.

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