There appears to be a pretty nasty memory bug when using DD-WRT build 14896 on a TP-Link WR1043ND router. From the Cacti graphs below it clearly shows a sudden drop off in available memory, then after a reboot things get cleared up again.
Seems others have had similar issues.
I intend to try the BrainSlayer r20675 release to see if that resolves the issue – and will report back.
[Update 14-Mar-2013]
Confirmed the BrainSlayer r20675 release firmware did the trick! Here are some new graphs showing no downtime with no complete memory drop-outs over 2 days with very high numbers of connected clients:
Darran Boyd 
What is the serial number of your router? is it 11xxxxxx, 12xxxxx or some other series?
Did you have wifi issues while running ddwrt?
11xxxx series
After 4 days no wifi issues. Looks like this image fixes the wifi issue for me. Thanks!
Good news!
Now for some bad news, the wifi drop issue is still present 😦
Just this time it took 5 days to manifest, usually wifi started ackting bad after 24-48 hours…
More info:
http://www.dd-wrt.com/phpBB2/viewtopic.php?p=747935
and bug report:
http://www.dd-wrt.com/dd-wrtv2/bugtracker/view.php?id=4388
I don’t why. I find this setting works: “Security mode set to WPA2 Personal and algorithm set to AES only”
http://mikebeach.org/2011/06/12/intermittent-wireless-connection-and-disconnects-with-dd-wrt-and-windows-7/
Hope it will help to find the bug.