Help needed - Problem with 3G[S] and wifi

[filberto]

I sold my iPhone 3g which could connect to my wifi router at home normally to get my iPhone 3G[s]

Anyway, the 3GS is not using the wifi. I connect to my router, and one of 2 things happen:
1) The wifi bar will come up in the grey bar at the top, as normal, but when I go to load a page/anything involving internet access, it disappears - leaving me using my cellular connection or saying 'phone isnt connected to the internet'.

2) I will select the router, and when I go Settings>wifi and press the arrow next to my wifi network, all the fields are blank. No IP address or anything.

However, rarely it does use the wifi, no reason why.

I've tried resetting network settings, shuffling wifi and airplane mode on and off to no avail.

I have restored once already and don't want to do it again unless its my only choice.

Any suggestions or ideas? Thanks for all the help.

EDIT: It's an iPhone 3GS Black 32gb, my network si fine as my laptop has no problem establishing and maintaining the wifi connection.

[Poseidon79]

Well you only have one other variable. Try connecting the 3GS on different wifi networks. If it connects you'll know it's a router issue. If it won't connect to anything then it's a phone issue.

[filberto]

Ok, I will when I get home. It does connect to my other wifi router more readily, but it also drops the connection there sometimes.

I think I will do a restore and then if that has no effect I will swap my iPhone at carphone warehouse some time soon.