I had issues with my 2790.
Firstly is the SSID hidden, and what encrytion is set up? If you have MAC filtering, have you added the iPaq's MAC address to the allowed filter?
Encryption IS case sensitive, regardless of ASCII or HEX WEP/WPA methods. So A7 is not seen as the same by some routers as a7. Also some routers don't need . or - between hex sets (ie a1b2c3 rather than a1.b2.c3 etc).
If you've exhausted all that, and still no joy, try Oddessy which is on the companion CD for your iPaq. |