Here's a router OS I think you should check out if you've got parasitic users on your LAN sucking up all your internet bandwidth. I've had it installed on my Buffalo WZR-G300NH for two months and it has been so awesome I have to tell everyone here on Hexus about it.
http://www.gargoyle-router.com/
It's a firmware based on OpenWRT that has been customised for easy bandwidth management. A quick summary of its noteworthy features;
- Independent and customisable ul and dl QoS
- Monitor bandwidth usage and connections by IP
- Monitor web usage and searches
and best of all;
- Set bandwidth throttles and quotas to individual IPs
It has been 100% stable for me. The only downside I can think of is the lack of some more-advanced features due to the focus on easy bandwidth management, but even moving from DD-WRT to this I've not missed a thing.
Give Gargoyle a try