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We have a D-Link DI-624M "Super G With MiMo Wireless Router" being used to provide wireless internet for roaming laptops in the office. The desktops are all using wired connections to a switch and working fine. The wireless connections to the D-Link router will connect and get internet access, however some sites work fine and some sites will not load. It is almost as if there is a firewall or filter/proxy set up blocking certain sites, however I have been through all the settings in detail and this is not the case.

As an example, google always works fine, but cnn.com never works. Similarly, I can ping google.com and get a normal response, but if I ping cnn.com I get a request timed out. This happens on any computer connected to the wifi. Again I've been through the router set up site and there is no firewall or filter for specific sites or IPs in place. I am stumped with this. Does anybody have any suggestions? Thanks!

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2 Answers 2

Ping is not the right diagnostic tool here. Cnn.com can't be pinged from my network either, probably because they don't allow incoming ICMP...

Start with the basics:

Do the wireless clients get the same ip configuration as the wired clients: ip address range, subnet mask, DNS server(s), default gateway?

Can you resolve (using nslookup) cnn.com from a wireless client?

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Thanks for the response! Regarding the configuration.. Wired - gateway: 192.168.0.1, subnet: 255.255.255.0, dns: 206.13.29.12. Wireless - gateway: 192.168.2.1, subnet: 255.255.255.0, dns: 192.168.2.1. Nslookup works from a wireless client, but shows that it is getting the DNS info from the wireless routers IP address and not our ISP's DNS server. Should that be changed? –  Joe Miller Jan 20 '11 at 21:38
    
Followup - strangely, CNN now loads in a browser, yahoo.com will not. Both resolve via nslookup. Perhaps I'm missing something simple here but this feels very random. –  Joe Miller Jan 20 '11 at 21:41
    
Of course, as soon as I write that and then try again, CNN is no longer working. –  Joe Miller Jan 20 '11 at 21:58

What this sounds like it a transport problem with your ISP. AS for you comment on the wireless clients getting DNS from your router that is the most common set up where the router acts as a DNS server for your network. One way to rule out your ISP DNS being the problem is to change your DNS to something like google DNS (IP is 8.8.8.8) and then check to see if things work better. The problem as you describe it sounds very much like a transport issue in your ISP's network.

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Thanks for responding! My only concern with blaming the ISP is that our wired clients are using the same internet connection and they have no problem at all, only the wireless clients are experiencing this. –  Joe Miller Jan 21 '11 at 0:57
    
it is just a very odd problem and I have found that most often these type of problems are due to intermittent problems in the ISP network. you might want to try shutting down all the clients and the router for about 15 minutes then bring the router up wait 5 mintues and bring up the client one by one and test them –  Liam Jan 21 '11 at 1:04

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