I have a 100MBPS Verizon router with 2.5 and 5 bands.  I only configured the 2.4 band with my new tp-link because thats all I needed

My speed tests are all 100 + MBPS with just my router ping times always low around 12 - 15 MS.  With my RE650 speeds are always about 50 MBPS.  The thing that really is more of a problem than just slow speeds is the speed seems to vary from 12 MBPS to 50 MBPS and ping times go all over the place also with some pings going up to 150 MS +. 

Speed tests are fairly consistent with just my Verizon router and all over the place with the RE650. One test might be 50 MBPS and 3 min later it might be 12 MBPS.  

I have the RE650 placed pretty close and it says it has full signal to my router. It is in the next room over.  

Any suggestions or how I might debug.