Can't wake Lion over wifi (or ethernet) using iPad and home sharing.

Question

I've upgraded to Lion and everything's fine apart from one problem: using my iPad to access home shared iTunes content on my mac no longer works when my mac is asleep.
That's a change in behaviour from Snow Leopard; I used to be able to sleep my mac and then wake it over wifi using either my iPad or iPhone to access all of my home shared libraries.  The mac screen used to light up for ten seconds and then go dark again, but it served me the files.
Lion seems to go into a deeper sleep which it can't be woken from.  If I attempt to wake my mac from my iPad within about ten minutes of putting my mac to sleep then home sharing seems to work and lets me use the home share libraries, but if I leave it any longer than that then the mac seems to fall into a coma and can't be woken.  The weird thing is that I still see a "shared library" folder on my iPad, but when I click on it nothing happens.  I think my Time Capsule is listening for wifi access and issuing the magic packet to the mac, but the mac just ain't listening.  
I'm using a Time Capsule in bridge mode from an ADSL modem and I've accepted a TC firmware update last week and I'm on lion 10.7.3.  I've tried using Ethernet to connect the mac to the TC (and temporarily disabled the wifi connection) but that still doesn't work.  Also, note I'm NOT suffering from the problem that 10.7.3 seems to be giving a few other people - my mac reconnects to my wifi just fine when I wake it up manually.  For the record, This was an upgrade, so there's still a tick in "wake on network" in power settings and home sharing on iTunes is still configured the same as it was before.
Does anyone have any suggestions about how I can get home sharing to work when my Lion mac is asleep please?
Jon

Answer 1

Jonathan:
The reworked release of the Combo came available the 2-nd or 3-rd of Feb, if you downloaded 10.7.3 complete after that date it will be OK already, no need to instal the Combo. But you can see the exact number of 10.7.3 in System Information/ Software panel: it should be 11D50b.....
fzahn:
I understand, I have TC and Extreme also, no need to set anything. And indeed I understand that it may be important for (as it is for me),
BUT even if it worked after you replaced the kext, I advise strongly not to read in an old kext over a new one, that may give other issues (you observed one already: Airdrop)... I hope you backed up the Lion one... for example such "replacing" was done in one (lousy) tool called TrimEnabler (to install Trim on a non-Apple SSD in the SnowLeopard OS): it replaced the whole kext. I read that there is a new version for Lion that just replaces the text piece that regards the identification for the Apple SSD's.... I do not dare to use such methods.... I advise to read the kext and compare the two (SL and Lion) and perhaps find a way to just replace the one string that is different (be sure it is precisely the same  lenth in caracters)...  BTW: after every update of Lion you have to do it again probably. Keep searching for a better way to solve your problem.
Did you do the firmware update of the TC and Extreme already?
BTW: there are two Airport Utilities for Lion: Airport Utility 5.6 and Airport Utility 6, the 5.6 is the "old" visual but in the new one 6 you can not change as many settings; if you want them both, change the name of the one you already have by putting the version number at the end of its name in Utilities, and install the other one, it will be installed additional not over.
Lex