I have a strange problem that I could really use some help with....
I have a Dual 2Ghz G5 Tower (running Leopard w/ 2 GB RAM) that all of a sudden stopped being able to connect to the internet.
I have tried resetting my Airport Express and plugging directly into my modem from the ethernet port and running all updates etc., with no luck.
Whether I connect directly via ethernet or wirelessly by Airport Express makes no difference, I end up with the same result of the network showing as being connected, but with a self-assigned IP address. With that, I have figured out it is obviously an issue with the G5 only, since I have a Macbook Pro and an older Powerbook that still connect without any problems.
Anyone know why something like this would happen and what I could do to fix it?
I would try a couple of things ... first power cycle your router (or whatever is supplying DHCP). Second try repairing permissions on the G5, maybe you have a 'stuck' lease file or something of the like.
Lastly, you can try setting up a manual IP address, just make sure it's in the same netblock as your router and that you assign the router address and DNS addresses properly (You can find this info on any of the machines that are getting DHCP ok).
Call your ISP. Tell them about the IP issue. They'll walk you through stuff at your end which you've already done dozens of times no doubt. Then they'll check their own lines, and see if that's where the problem is.
Did that. Called Rogers the day it started happening and they asked me to reboot the modem, the router and check network settings. After the tests with Rogers Tech Support, they told me to contact Apple as it seems to be a hardware issue on my end.
I also just tried starting up with the Leopard disk, and ran Disk Utility. Checked the disk for errors, then repaired the permissions that had warnings that Disk Utility reported. Restarted the computer, and checked again to find the same self-addressed IP problem.
Is there some kind of reset on the computer that might help? I can't imagine what hardware would have to be replaced...
I have also tried to enter a manual address in the DHCP settings as well. It entered correctly without any issues (i.e. is showing in Network Settings that it is connected with an ip address of 10.0.1.2), but after a restart it is still getting the same ip error.
I replied to another thread in this forum yesterday concerning a similar problem. A few weeks back I started having the same problem as you where I was connected to my wireless network but with a self-assigned IP. Note this happened after I updated the system software on my Powermac G4 running 10.5.1, similar to you my powerbook running 10.4 remains unaffected. After trying several things, this is how I fixed the problem:
1. Go into your browser and access your router settings, this can be done in the following manner: http://192.168.1.1, enter in your admin and password to access. Under the "wireless" tab, click on "basic wireless settings" and change the wireless network mode option to "B-only". If it's already set to that then don't change it. Then click on the "Basic Setup" link, and note the Local IP address, Subnet Mask, and Static DNS1, if there is not Static DNS1 listed, go to the Status link and there should be one listed there.
2. The only way I could then connect to my wireless network, was to manually set all of the parameters. So if you go into System Preferences > Network > Airport, configure IPv4 using "Manual". You can enter in the IP address, Subnet Mask, Router, and DNS server information as noted above.
For example the IP address, choose something like 192.168.1.110; Subnet mask should be something like 255.255.255.0; Router should be 192.168.1.1; and DNS Server should be whatever you noted above.
This should enable you to connect to the internet, your wireless network, and should stop your IP address from being self-assigned. Since you've specified a static IP and even if the router refreshes you'll always get the same address. If you need any further assistance please post and I'll see what I can do but this fixed the problem for me and will not have any affect on the other computers that use your wireless network.