Windows – Can’t get internet on 2.4 GHz wifi, but can for 5 GHz

internet connectionwifi-configurationwindows 7wireless-networking

I have a Windows 7 desktop that is giving me a baffling network problem. My router is broadcasting two wifi signals: one on 2.4 GHz and one on 5 GHz. My desktop can connect to both, but cannot get internet when on the 2.4 GHz one. I would just happily use the 5 GHz network, but it is an extremely weak signal and cuts out frequently. The 2.4 GHz signal is stronger.

Many other computers in the house happily work on the 2.4 Ghz network, so I feel as though the problem is with my desktop, not the router configuration.

Things I've tried:

  • Resetting everything I can about the Windows network configuration
  • Uninstalling the wifi adapter drivers and reinstalling them
  • Setting a static IP instead of the dynamic IP
  • Using different DNS servers
  • Disabling encryption on the wifi
  • Turning off the Windows firewall

When I ping sites from the command line, it works! When I try the Windows 'Troubleshoot problems', it acts as though everything is fine. But I can't load any webpage through any browser, unless I connect to the 5 GHz network. I'm stumped!

Additional information to answer commenter questions:

  • The adapter is internal: an Asus PCE-N53.
  • I do get a valid IP from DCHP. The router shows the desktop in its list of connections and everything looks normal.
  • I cannot access other computers on the network.
  • The signal strength is decent and moving the antennas or computer doesn't improve the situation. The 5 GHz signal is much worse, but I can manage internet on that one (though not reliably).
  • I've used inSSIDer, and there is no other network on the same band, so congestion shouldn't be an issue.
  • Changing the router to N-only didn't change anything – it still works on other computers, but not on my desktop.
  • Browsers don't give informative errors – they just time out.
  • The Asus website has only one driver version (1.0.0.8), so that's what I'm using.

Interesting update: while pinging worked before (for both IPs and hostnames), it no longer is. And now the Windows troubleshooter is reporting that 'The DNS server isn't responding'. Not sure what's changed, but everything else is still the same: 5 GHz works, and 2.4 GHz works for all other computers.

Final (perhaps) explanation: I managed to dig up an old USB 802.11g wifi adapter, plugged it in, and everything works perfectly with it. So I strongly suspect that the Asus PCE-N53 is the culprit. I'm not sure of the exact explanation (perhaps the Asus adapter is broken?), but I may just choose to replace the adapter and consider this a closed case. Thank you to the commenters for their suggestions, though.

Best Answer

I am pretty sure there are some remnants of an old connection or configuration, which is potentially causing an issue in regards to the the Wi-Fi Connection.

Give this a try:

A) Disconnect from all Wi-Fi access points, then set your computer to airplane-mode.

B) Open PowerShell OR Command Prompt as administrator.

C) Enter into the command-prompt or powershell: ipconfig /flushdns

D) Enter into the command-prompt or powershell: sfc.exe /scannow ...wait for it to complete. This should only take a few minutes.

E) Shutdown the machine (don't restart it); we need it shutdown(powered off completely) so that the wireless adapter can be "restarted".

F) Wait for about 10 seconds ===> then proceed to power it on.

If that doesn't fix the problem then my only last suggestion is to change the Wi-Fi channel on the 2.4 GHz band.

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