Welcome ,I will give a full and clear answer to your question, please make sure to reply to any questions I have. They may be essential to my reply.
Hi , lets try a few settings .
Before configuring or adjusting specific settings, perform the following steps:
Ensure that your Wi–Fi router's firmware is up to date.
This guide to update your apple router is required . http://support.apple.com/kb/HT1218
If you are using a wireless network with airport you may want to check your Wifi channel is not clashing with other nearby network/s , details below .
Extra wireless setup info :-
Things to do before/during setting up your router :
Find a clear channel :
Try to pick a channel no one else is using next door , this tool can help find a clear unused channel . .
WiFi Scanner v1.1 **use this to check your wifi on the mac is working too :)
Once installed , look inside your Applications folder to see the app , Wifi scanner .
Launch it , and find out if there's any other networks in your area , and what channel their on , you don't want to be on the same channel so set your router to another channel in the mid range , channel 5 , 6 , 7 or 8 depending on other wifi networks close to you etc .
Normally you can get in to the router Airport setup via Airport utility .
Mac HD / Applications / Utilities folder , Airport utility .
From here you can normally configure the Airport router and setup a SSID and password for wireless use , you want to change your Wifi wireless channel as found above to a clear channel , preferably at least 1 gap in channels from any other networks nearby ..
If your Wifi channel is set to 7 and a other local wifi network is set to 8 set yours to 6 , if a nearby net work is set as the same channel as yours 7 & 7 for example set yours to either 5 or 9 and so on for best results.
If you have Wireless phones at your location including mobile phones and home phones , relocate away from the router or computer as signals can affect wireless reliability. Or switch off to test if there is an affecting issue .
Normally the affect would be worse during calls if any are made . .
You can set the dns setting in the router also please do so .
Enter the DNS info below:-
More DNS info here :-http://www.opendns.com/
for devices :
See DNS settings for your Wireless network and devices there are way to do this on each device , router , macs network control panel , iOS settings for Wifi on iphone and itouch , ipad etc. .
See DNS control panel Tab in the Apple menu , System preferences, Network control panel , DNS tab. .
For iPad , iPhone , iTouch .. please go to the Settings app , Choose Wifi , Choose the SSID your router then hit > See DNS settings , fill in the DNS info as below .
Enter the DNS info below for your DNS setup :-
Does this help?