Slow Local Network, Windows 7, Snow Leopard, WiFi/Wired

Question

I am experiencing really poor local network performance in my home. I was recently using a Linksys WRT54G Router with DD-WRT on it, and a couple comparable Linksys-G PCI cards for connectivity but decided to upgrade hoping it would help with my performance issues.

The computers in my house are connected as follows:

• Comcast Business Class Commercial 25mbps/10mbps (Verified)
• D-Link DGL-4500 Wireless N Router
• Windows 7x64 - D-Link DWA-552 Wireless-N
• Windows 7x64 - D-Link DWA-552 Wireless-N
• Mac Mini 10.6.2 - AirPort Extreme N
• Playstation 3, Hard Wired
• Xbox 360, Hard Wired

Essentially the problem is very specific. Web browsing and uploading/downloading files from the internet is fine, more than fine.

But if I want to say, Stream a video from one of my Windows 7 computers to my PS3, or copy a large video file between either of the PC's or the Mac, I get a consistent 500-900Kbps throughput at the high end.

If I open my network browser, or try to browse my homegroup the response time is horrible.

Both of my Windows computers are showing Strong wireless signals with a connection speed of 300Mbps. I know I can never expect to achieve anything near those speeds, but 500Kbps?

Here is what I have tried so far:

• Enabled Single mode N-only and N/G Only on router
• WPA2 with AES Encrpytion
• Disabled "Remote Differential Compression" in Windows 7
• Disabled TCP "Auto-Tuning"
• Used other software for file copies such as "Teracopy"

I am at the end of my rope. Unfortunately I live in a 75 year old home with plaster walls, so hard-wiring my entire house isn't really an option I can handle right now. Any ideas to help me get decent speed when transferring files across my network would be greatly appreciated.

Answer 1

Some thoughts of things to try...

• Make sure the firmware is up to date on your wireless router, and that the wireless card drivers are up to date on your Windows clients. Ought to update the Mac mini to 10.6.3 while you're at it, since that update contained some AirPort driver updates as well. No use fighting bugs that may already be fixed.

• If you move the wireless machines into the same room as the wireless router, do you get decent performance? (Never trust the signal strength meters in 802.11 products -- it's in the vendors' best interests to almost always show strong signal strength, because it reduces the number of tech support calls.)

• To see if your wireless router itself is at fault, try enabling Internet Sharing (from Ethernet to AirPort) on your Mac mini. This puts the Mac mini's AirPort card into full software AP mode, so it's acting as a full-on wireless router as opposed to IBSS / Ad-hoc / Computer-to-Computer mode. Then associate your Windows machines to the Mac's wireless network and see if your Windows to Windows file transfer performance is decent.

• Another interesting test would be to get those D-Link DWA-552 cards out of the picture. Perhaps you could hard wire one of your Windows boxes to the router, and then transfer a file between the (wireless) Mac mini and the (wired) Windows box, and see what your transfer rate is.

• IPerf is a simple command-line tool that's used quite a bit in the networking industry because it's great for more reliable measurements of network speed than you're likely to get with a file copy or HTTP download or video streaming. You can do a simple 60-second TCP test like this:

  One machine is the IPerf server:

  iperf -s -i 10

  The other machine is the IPerf client:

  iperf -c $IPOfIPerfServerBox -i 10 -t 60

  I recommend that you do your performance measurements with IPerf, so you don't have to wonder if the real bug is with, say, the SMB (Windows file sharing) client or server in your Windows boxes.

• By the way, your D-Link DWA-552 cards are kind of a mismatch for your other wireless equipment. Those cards only support the 2.4GHz band, whereas your router and your Mac mini both also support 5GHz. The 5GHz band is far less likely to have interference, and it also allows you to use 40MHz-wide channels for full 300mbps throughput while still leaving room for other users of the band. If you try to use 40MHz-wide channels in 2.4GHz, you'll likely kill Bluetooth and anything else trying to use the 2.4GHz band (cordless phones, baby monitors, wireless webcams, wireless A/V relays, and more). If it's not too late to return those cards for a refund, I'd recommend you return them, pick up dual-band cards instead, and move your network to 5GHz (preferably the upper 5GHz band, like channel 149, 153, 157, or 161).