I set up a new b210 last week and assuming you are not using any network other than the printer's own network, I found that sometimes the printer has to be rebooted [turned off, then on] and then the printer network reset up on the iOS device so the iOS device can receive the wi-fi signal broadcast by the printer.
So reboot the printer, then go to settings on the iOS and find the printer network setting.
01-06-2011 09:58 PM