wireless client can acquire an valid IP address but can't access internet

[csco11121655]

Hello,

our company have one SSID that authentication by add the exact MAC for the Scanner. Now only one of them is OK, the other five can't access any intranet/internet resource. all of them can connect the SSID and acquire a valid IP. and checked both the work and doesn't work's IP in the some subnet and been assigned the same DNS setting. for the not work one they can't even ping their same subnet's gateway. we have allow these not work device connect to other SSID. it's all ok for them. the issue happen after an power outage. 

could you give some suggestion where i should check/the issue me caused by?

thank you.

[ahakels]

Please Check your connectivity to devices hop by hop like :

1.End devices to AP

2. then AP to SWitch

3. Switch to WLC

4. WLC to router/firewall and

5. Last router to internet.

6. confirm that DNS is working ok.

7. Confirm that end devices are getting the IP's from pool assigned in DNS

8. refer the following guides:

http://www.cisco.com/c/en/us/support/docs/wireless/aironet-340-series/8117-connectivity.html

https://supportforums.cisco.com/document/51626/wifi-troubleshooting-cheat-sheet