about share internet in 10.7

I am using i-mac os 10.7, just test the internet shareing.

I have connected mobile+notebook already to work on about 2 hours..but after 2 hours it always cannot go to any web site.

but in this period, my i-mac is ok to go website, only other sharing device cannot go any website . But the wifi connection is still connected..

seem if I Restart the mac, then other device will be normal, but after 2-3 hours,it will happen again.....
any idea? or it limited to only can use 2 hours?

On your laptop, make sure it is getting a correct internal IP address and correct DNS server address.

..

in mobile/notebook,it showing
10.2.x.xx
DNS 10.2.xx.xx too
my mac share name = testing, I confirmed other device is connected to 'TESTING' already...thanks
is it right?

and I using WEP 64bit pwd only.