Hi Guys, I heard that there is some limitation with the Wi-Fi and Android Phone. I have the similar kind of problem for my Nexus S when my phone got upgraded to 2.3.6 via OTA. However i was able to solve the problem by changing the below settings in my mode / Wi-Fi router.
Have Updated the Wireless channel to 4 and enable Security Mode as “WPA/WPA2-Personal(PSK)" & restart the modem, thatz it. it started working fine.