uff, I'm sorry tugaraptor but this error means that your Wifi is broken.
It's a hardware error (from what Sony says) and it doesn't depends on the firmware.
One explanation about the issue is that the custom firmware works with higher Mhz than the offical firmware. It causes that the Wifi anthene gets hot and it comes unstuck. Then the wifi doesn't work.
My advise is if your PSP is in guarantee, return to an official firmware and try to change it.
I hope it helps for you