You may have to acquire an earlier model AirPort base station, such as an Express from a
similar era of portable computer vintage for best use with these; wireless security protocols
for the older gear is not the same as for later, so you'd find the iBook G4 with Tiger 10.4.11
to prefer either WEP or WPA, the latter is better and newest of these. Depending on which
iBook G4 models you have, their internal specifications may have direct bearing on how
they would connect to the internet by wi-fi and their correct settings or limitations.
Earlier iBook G4 (like other PowerPC early G4s) were supportive of the older 801.11b/g
and did not support security protocols such as WPA2, unless they had sufficient hardware
to run Leopard 10.5.8; usually WPA could be available in USB2.0 series late iBook G4s
with Tiger 10.4.11; mine has 10.5.8 installed, with 1.33GHz last-model iBook 12-inch G4.
Older hardware information could be checked online at everymac.com to see the wi-fi spec.
The Apple Support spec pages for old vintage/obsolete hardware are more difficult to find.
Here are most/all iBook G4 series (white-dual USB, later models) specs from everymac:
•iBook G4/800 12-Inch (Original - Op) 800 MHz PowerPC 7457 (G4)
•iBook G4/933 14-Inch (Original - Op) 933 MHz PowerPC 7457 (G4)
•iBook G4/1.0 14-Inch (Original - Op) 1.0 GHz PowerPC 7457 (G4)
•iBook G4/1.0 12-Inch (Early 2004 - Op) 1.0 GHz PowerPC 7447a (G4)
•iBook G4/1.0 14-Inch (Early 2004 - Op) 1.0 GHz PowerPC 7447a (G4)
•iBook G4/1.2 14-Inch (Early 2004 - Op) 1.2 GHz PowerPC 7447a (G4)
•iBook G4/1.2 12-Inch (Late 2004 - Op) 1.2 GHz PowerPC 7447a (G4)
•iBook G4/1.33 14-Inch (Late 2004 - Op) 1.33 GHz PowerPC 7447a (G4)
•iBook G4/1.33 12-Inch (Mid-2005 - Op) 1.33 GHz PowerPC 7447a (G4)
•iBook G4/1.42 14-Inch (Mid-2005 - Op) 1.42 GHz PowerPC 7447a (G4)
You may be able to run a second older version AirPort express from an Ethernet port
on another base station or the main cable or ISP router; or check into a bridge so as
to share the internet source across more than one kind of wi-fi spec. Another option
that some may use to try & connect, would be to shut down all wi-fi security from the
main wireless base station. Not a great idea, except to test connections with older gear.
Later gear also may require different passwords whose length may not work w/ old
Macs; but the protocol and hardware -related issues may be why they won't connect.
•Solutions for connecting to the Internet, setting up a small network, and troubleshooting - Apple Support
•Creating a small Ethernet network - Apple Support
https://www.google.com/?gws_rd=ssl#q=wi-fi+to+old+iBook+G4+from+new+wireless+rou ter
The first-generation AirPort Express would like be helpful, or a little bit newer:
http://en.wikipedia.org/wiki/AirPort_Express
With more information on a specific iBook G4, the hardware question of supporting a
later or more recent wi-fi security protocol and settings may be more easily answered.
Good luck! 🙂