Hello there,

Could you try flushing your DNS.

Power off your modem/router for 5 minutes, turn it back on and then perform this command.

Windows XP:
- Click Start and then Run
- Type cmd in the run box and click Ok
- In the Command Console window that has appeared type: ipconfig /flushdns
- After typing the above command, press Enter to execute it and then close the window

Windows Vista / 7:
- Click Start, then Programs, then Accessories and then locate 'Command Prompt'
- Right-click on 'Command Prompt' and left-click on 'Run as Administrator'
- In the Command Console window that has appeared type: ipconfig /flushdns
- After typing the above command, press Enter to execute it and then close the window

Please also make sure that your Firewall has an exception listed for World of Warcraft, you may need to consult with the Firewall creator's website for assistance regarding this.