Regardless of whether I'm using 2.4ghz or 5ghz performance is terrible and inconsistent. Over Ethernet I haven't tried as it's not practical. 

My plan is 100/100 my cheaper Tenda router gives 93/95 over wifi consistently, with this one it's sometimes 80+ but mostly 40-50 range and speed test and gaming stutters a lot.

I'm on PPPOE,

2.4 ghz 40mhz/channel 6/ 802.11bgn

5ghz 80mhz/channel 44/ 802.11a/n/ac mixed

google dns