I have here two phones that both exhibit the same symptoms. One is a samsung GT-S5570 running the stock ROM, the other is a Galaxy S2 running an AOSP-based custom ROM. The problem I have is that while they are connected to the wifi and are able to browse web sites, etc, they periodically stop accepting incoming connections and/or responding to pings. In order to get them to start responding again I have to disconnect and reconnect the wireless connection. Yet they are still able to make outbound connections.
Any ideas what may be causing this (somewhat bizarre) behaviour or how I can stop it?