Samsung Tab4 slow wifi on fast network please help.

[NCHornet]

Have a WRT1900AC Router on Timewarner Cable internet. On my Nexus 6 and my HP Laptop I am getting 206 to 225 mbps on speed test wireless, but on my Tab4 on the same network and the test results are 70 to 90 mbps but have dropped as low as 28 mbps. I have reset router and modem and tab 4 several times with no change. Any ideas?

 

[B. Diddy]

Does the router have a QoS (Quality of Service) option in its settings?