I have a Macbook 5,1 Late 2008 Unibody running Yosemite 10.10.5 suffering from wifi issues. I have 300 mb/s or more internet speed and the macbook is only doing about 2 mb/s or nothing at all. I use my other computers and they work just fine (no problems with the router either) so I know it's just this computer. When I use an ethernet cable it gets normal speeds. I've gone into system information and it shows wifi card info. I've tried everything including resetting pram, deleting the wifi plists in /library/.../systempreferences/. Deleting and the recreating the wifi under network in the system preferences. Firmware all looks up to date. Any idea what the problem may be and how to fix it? Thanks in advance.