AC1900P Router mode

I have the AC1900P and I can't get this thing to download over 800Mbps and sometimes much lower (very inconsistent). If I set my modem to gateway mode and my router as Access Point mode or just use my modem without the router. I can download at 955Mbps but the bufferbloat is terrible when the modem is on gateway mode and wifi range sucks. I have everything turned off Traffic Anaylzer, QoS, and AiProtection.

Any suggestions? Bad router maybe?