why doesn't it renew DHCP lease when waking up?

goto Preference Energy saving settings and where it says put computer to sleep say never & the display you can put what ever you want

Hi,

No, it just means the computer will not go to sleep on it's own... you will have to put it to sleep using the Menu under the Apple Icon.
How does it go to sleep now?
how long do you have the DHCP set for?

Enjoy

Hi again,

If you are connected with a Linksys router to the Ethernet, why are you using DHCP? I am connected by Ethernet to a cable router using the 'Automatic' setting for the Ethernet. The DHCP set-up did not work for it, so I let OSX do it the way it wanted to, on Automatic. Maybe that is why the lease renew does not come into play for me... altho I set it to max time. And I do put mine to sleep, two ways: one is manually, the other is on time-out thru the Security Menu in System Preferences.
DHCP must not be so friendly with Mac's other features.

Enjoy

Hi again,

Looks like you are using OSX 10.3.X, which is what I have, so the screens/menus should be similar.

The way I ended up doing it (hardwired... I also had it wireless, but have better speed wired... left the printer wireless tho). Go to the upper left Apple Logo, click, "Location" > "network preferences". Once inside, you see 'Location' > choose "Automatic"; next you see 'Show' > choose "Built-in Ethernet"; click the (TCP/IP) button; next, under 'Configure IPv4' choose "Using DHCP"... do no more on this menu... click the upper (Ethernet) button; down to 'Configure' > choose "Automatically".
If you were plugged in with the ethernet while doing this, all the numbers should of come up while you were watching, don't forget to click (Apply Now) at the bottom right.I have noticed that my (Renew lease) is not there anymore, must not be needed... in the Auto mode. The other upper options (PPPoE - AppleTalk - Proxies) are out of this picture, they do not apply.
If done this way, you should have the best of both worlds, sleep and wake with out reseting each time.

PS: The first time I did this after clicking apply, I had to leave it plugged in, but shut it down and restart it for the router/computer to line-up (or whatever they do). Leave the ethernet plugged in around the clock, in sleep, the ethernet is out of service, until you wake it up. Once we lost power, and the router shut down while plugged in, had to do the computer shut-down/ restart to get it back.

Have Fun