Internation Unlocked Version WiFi problems

[kirby3021]

I have a Galaxy S3 i9300 16GB Factory unlocked international version. The wifi reception is very weak, even though I can connect with my old iPhone and my laptops just fine. I've tried turning off the WiFi power-saving mode, I've tried the fix where IP Address, Gateway and such are entered manually. I've tried turning off various settings in wifi (Network connection, Check for Internet Service) and changing the WiFi frequency band (oddly enough, it got up to three bars for just a second when I did this before dropping back down to one bar). Has anyone with a similar model had these same problems and found a fix for them?