Welcome to the forums, Peter.

Software updates will often cause the device to loose it's IP handshake with the router you're used to connecting to.

The remedy is to restart the router, allowing a new matchup.

I'd also reboot the phone, once the router has fully finished its restart routine.

 

The best thing to do is to turn your phone off and then turn your router off. Then after 30 sec turn both on. Then try to connect to the wifi, if you cant do it then its the drivers that you will need to get installed.

 

im having same problem too it says connected and obtaining ip adress but then disconnects and just keeps looping around i can connect to internet and send mms messages after inputting settings back in manually which update had wiped clean but wi-fi is still a no no any body help us solve this problem wi-fi is ok with laptop so no prob there and all worked fine until froyo update