No DIR-632 forum, so I'm posting here. Several months ago, someone posted a similar problem and I didn't see a solution, so I'm trying again.
For me, the wireless will stay active indefinitely, working fine for my Android and Apple devices, as well as all of the wired devices I have connected. Even my Windows 8 laptop works fine. When a Windows XP/Vista/7 device connects, the wireless locks up within a few hours. Most of the time, I can reset it from the wired desktop, but occasionally, it locks up so badly that I have to power down and hard reboot the router.
I've tried several of the suggestions on previous iterations of similar posts, including changing the channels, switching between G and N, etc., and I'm not certain that the problem is in the router per se, but somewhere in the interface between Windows and the router. The solution might be a change in the Windows environment, but I have not been able to find one yet.
Anyone have some suggestions? I'll post particulars about my system settings later this evening.