I have Jailbreaked my iPhone 3Gs but after the jailbreak I noticed that the WIFI is very very poor, even if I am very close to the WIFI adapter. this is the second time as I faced the same issue on another iPhone 3G.

the problem is that it will not fix even after I restore to the factory default or even if I downgrade the iOS.

here are additional details may be helpful
- the iOS for the 3Gs is 5.0.1
- I used the redsn0w latest version (redsn0w 0.9.10b4 for Windows)
- I don't remember details about the versions of redsn0w or iOS of the iPhone 3G (it was a while ago), but sure that they were the latest up then
- this is not the first time or the first iPhone that I jailbreak, so I know what are the steps
- this is not the first time to jailbreak this particular iPhone (it was Jailbroken on earlier version of iOS)
- I faced this problem on the iPhone 3G while on on the 3GS using the same versions of iOS and redsn0w earlier
- Once this problem happens there is nothing can recover, seems like it affecting the hardware or something that is not changeable by changing the iOS

here are some details about the troubleshooting I have done (all unsuccessful)
- restore from earlier versions
- reset the network configuration
- reset All Settings
- reset All Settings and Content
- restore factory defaults from iTunes
- downgrade iOS

but all unsuccessful
Thanks in advance for your help