Powerbook Won't Connect To Router

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Hey guys,
I have just acquired myself a powerbook G4 to use as a server. At home, it can connect to the router (airport extreme) fine with no problems, but now I've taken it down to uni and it is refusing to connect to the router supplied by O2. I have the right password for it and when i type it in, it says that there was an error joining the network. I've changed the frequency of the router multiple times to get it to work but to no avail so was wondering if any of you guys could help?
Thank you kindly

 

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I've just been playing with it a bit more and when connected directly to the router with ethernet, it shows a connection and works fine but when trying to connect via wifi, i get the error message "There was an error joining the Airport network "[Its name]"". Is there anything i can do? Its running 10.4.11