Atheros Wireless 802.11n Windows 7 – unable to ping default gateway

This had me foxed for quite a while… I’m still not sure of the actual root cause, and this is only a workaround.

So… Bought a Zoostorm SL8 Windows tablet for work. Got it connected to the WLAN at work which runs via a Cisco access point, it’s 54Mbps 802.11g unencrypted using MAC address filtering (yeah, nasty, nothing to do with me). Anyway, the SL8 connected fine and was working quite happily (until I joined it to the Active Directory and had to work out how to do Ctrl-Alt-Delete without an on screen keyboard – it’s actually just a case of pressing the “soft” button on the front of the SL8 then holding the power button at the back for a few seconds – but it’s not mentioned in the Quick Start Guide). The SL8 arrived on a Thursday, so I had two days at work with it, then it was the weekend. Obviously I had to take it home over the weekend to play with.

So, I got it home, connected it to my Virgin Media WLAN, which runs via a Virgin-branded Netgear VMDG280 combined cable modem, 802.11n wireless access point and 10/100Mbps switch. I use WPA2-PSK (AES) wireless security. I have various things connected to this and working fine. So I was a bit surprised when Windows 7 Professional on the SL8 claimed “no internet access”. My laptop runs Windows 7 Enterprise and works just fine on this network.

Apart from the “no internet access” Warning triangle on the wireless network indicator in the notification area, the other things worth noting on the SL8 were:

  • DHCP appeared to have worked fine
  • IP address allocated was valid and there was no conflict
  • DNS servers were correct
  • route print command showed nothing unexpected
  • all the above settings/values were comparable with my Windows 7 laptop
  • I could not ping the default gateway (i.e. the Virgin/Netgear VMDG280) from the SL8 but could from everything else
  • A continuous ping of the default gateway was not giving consistent responses, sometimes it was “Request timed out.”, others “Reply from 192.168.0.9: Destination host unreachable”, while other times, occasionally I would actually get a working response “Reply from 192.168.0.1: bytes=32 time=889ms TTL=64” albeit with a pretty massive latency.
  • There were no group policies applying
  • No IPSec rules defined
  • I reset TCP/IP via the netsh int ip reset command, rebooted, no change

Annoying huh?

So the SL8 worked ok on the work network, but not on my home network. Yet other stuff (laptop, Android phones) were quite happy on my home network.

Then I tried using the Wi-Fi Hotspot app on my HTC Desire, and joined the SL8 to that. I also use WPA2 (AES) on the phone whenever I use the WiFi Hotspot app. I had internet access.

So what’s the difference between the work WiFi, home WiFi and phone WiFi? Work and phone are both 802.11g 54Mbps, the home WiFi is 802.11n 300Mbps. The Atheros AR9002WB-1NG combined WiFi and Bluetooth adapter in the SL8 is 802.11n capable whereas the WiFi device in my laptop isn’t. So I think it’s something wierd with either the Atheros hardware, driver, or 802.11n itself.

The VMDG280 access point has the ability for you to limit which version of 802.11 it will use: go to Wireless Settings, then change the 802.11 mode – I changed mine to Up to 54 Mbps, and a few seconds later the SL8 was working normally, pinging the default gateway, browsing the internet etc. Interestingly, the ping response time was now a perfectly acceptable 1ms.

The suspect here is either some security feature in the 802.11n protocol that I don’t now about, or something broken/not configured properly in the Atheros driver/hardware. It could also conceivably be a problem with the 802.11n imlpementation on the Virgin/NetGear VMDG280. Annoyingly the Qualcomm Atheros website makes zero mention of driver downloads, or support or anything handy like that. So quite where we’re supposed to get that from I have no idea, not good. So I can’t try a new driver, the one I have is version 9.0.0.222 dated 08/07/2010.

So it’s a workaround, but it does the job.

This entry was posted in Hardware, Windows and tagged , , , , , , . Bookmark the permalink.

3 Responses to Atheros Wireless 802.11n Windows 7 – unable to ping default gateway

  1. rcmtech says:

    I recently had a new Atheros driver appear via Windows Update. I’ve installed it but have yet to see if it fixes the problems above. The new driver version is 9.2.0.427 dated 21/06/2011.

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