Internet speed cut in half suddenly

Hello,

My wireless router pushes 36Mbs, it still does on my tablet, but my ps3 connection suddenly dropped from 18Mbs to 9Mbs download. I hooked it up wireless and same speed of 9mbs. I did factory reset and didn't help. Switched router and still the same. Even tried a different DNS. I know the problem is the ps3, but why all of a sudden. It's a 120 GB ps3 slim. I take very good care of it, keep it clean and always plug directly into wall.