This is the same issue that I had in this thread, but the problem has started again. I am running Davidc502's OpenWRT build, but I'm posting here because the problem happened on regular builds as well.
My wireless connections have randomly started dropping internet access. The wifi stays connected, but nothing connected to the wifi can connect to the internet. My wired PC is unaffected and can access the internet just fine. Restarting the router fixes the problem temporarily, but the connection drops again anywhere from 2-30 minutes later.
There's nothing immediately obvious when viewing the logs, so I'm really not sure what's going on or how to troubleshoot it. Any help would be greatly appreciated.