I have a samsung galaxy s3 i9305 LTE and I have been using this device without problems for around 2 years now. It runs on Jellybean 4.3 baseband version i9305zhucnb1. It has been running on this firmware for a couple months now ever since it has been rolled out. The problem is, the WIFI suddenly stopped working. Never had this problem before and I actually never had any problems with this device ever. Whenever I turn on WIFI, it detects my home networks and other networks wherever I go but whenever I try to connect, it just shows saved secured, and sometimes authentication error after a couple of attempts. I have other WIFI devices at home and all are working perfectly. I tried forgetting the networks and I am positive that the WIFI password is correct. I tried to restore the device to facroty settings hoping that it would work. I tried accessing my router and I'm sure my device isn;t blocked. I even configured my routers to only accept the mac address of my device and block all others but still wouldn't connect. I tried rooting my device via odin but my device blocks root access and shows the error message "an application attempted to access system on your device without authorization. this attempt has been blocked.". I tried rooting it to try flashing custom roms. I also tried dialling *#0011# to configure my wifi but it still does not work. I don't think that the problem is my firmware because I had it for months and it didn't update before the issue occured. I was also about to try downgrading it to an ICS stock rom since I can't root it to try custom ROMs. I've been trying to fix this for days now. Can you guys give me a step by step instruction on how to fix this if it is at all possible? And maybe give me a link where I can download ICS or lower stock ROM's for this device. I think I have to use a TGY firmware, though I don't have an idea what it means. Thanks!