to be honest, to many entry level routers, dd-wrt is unstable. fallback to stock firmware could deliver better result. Or go for Gargoyle if your router is being supported.
Gargoyle (base on openwrt) can be classified as a light weighted openwrt with better stability. But the list of supported router models is a bit limited. I've been using Netgear 3700v4 with Gargoyle for 3 years+ and it's extremely stable.