Thanks for the answer, I'm having a hard time to downgrade firmware now, how am I supposed to do it? When I try to revert it using older firmware it throws error, that the version is incorrect.

Region : Poland Model : TL-WDR4300 Hardware Version : V1 Firmware Version : 150302 ISP : UPC Hello! I see it's a pretty common issue, but I will give it a shot. I updated my router to the newest...