Are you using WEP or WPA2?
If you are using WEP (which I guess from your reference to the default password), you should have considered to take @bko's advice serious.
The Core might work well, but the Photon uses a different brand WiFi module, hence there was a thread about the peculiarities of WEP on the Photon
But my personal advice would be to use WPA2 instead of WEP otherwise you can leave your WiFi open just as well.