Default WiFi speed issues... Already googled

So I originally had issues with LTE speed and WiFi when I first got the phone and ended up getting a HTC One M8 and kept both (I do development for my company so why not have more test devices I guess). I just picked up the gs5 again and updated the firmware and while LTE seems as good as it gets for my area, WiFi is still horrible.

I have the 300gigabit/second fiber from AT&T and a 802.11ac router with WPA2 security and my other devices get between 150gigabits/second and 250/second. My M8 just did a test and it was about 160 whereas this does between 40-60.

I know it has to be something with my individual device because I've seen speed tests on the forum that are what I should get.

Any ideas for what could be the issue? Using the stock deodex room rooted/unlocked.

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