OK. All you geeks. I'm sorry for claiming that Macs are easy.
We have two iMacs in the study. Also an Airport Extreme wireless router. The new iMac sees the router, delivers the internet, no problem. The old iMac can't see the wireless network. I've checked the seating of the airport card and antenna. All seems fine. The Mac says that Airport is working, but isn't connected to a wireless network. Trying to connect to the wireless network (with its regular password) fails.
OK, here's the freaky bit. If I use the Airport Setup Utility, the old iMac instantly spots the Airport Extreme, gives it its correct name, can interact with it and reboot it etc.
I have tried things like turning airport off and on, rebooting, and so on, and have checked all settings. Plugging in an ethernet cable gives Internet; it also gives a tripwire across the study floor.
Tips welcome.
- I am so eating crow
I've done this dance occasionally, and its usually solved by judicious power cycling and rebooting the macs concerned.
Do you have any access comtrols in place? Does the network pane in system preferences provide any useful diagnostics?
It doesn't have any DHCP settings becuase it tells me it's not connected to an Airport network. It would pick them up from the network, yes.
There are very few network settings because of this.
I have restarted every relevant bit of kit with a plug. Mostly several times.
One quick test would be to borrow a non-Apple wireless router off some one, and see what happens...
Since the old iMac can find the base station when it's running Airport Setup Utility, that means its Airport card and antenna are working. Since connecting via an ethernet cable works, that means the base station is at least mostly okay. This appears to isolate the problem to two possibilities: the network settings specific to Airport on the iMac, or access controls on the base station.
The suggestions about rebooting are good. If the base station is being used as a router with DHCP, clients will ask the base station to assign them an IP address when they come up. To ensure that clients get usable IP addresses, turn everything off, boot up the base station first, then one client at a time. After powering up each client workstation, go into its network/Airport settings and note its IP address. Try configuring the problem iMac exactly the same as the one that works, and power it up before the working iMac (to see if it might successfully take the working iMac's place).
Good luck!
Generally speaking, Macs are vastly easier than most. This is unusually hard.