RAX40 slow wifi, good speedtest.

I recently purchased a RAX40 (Firmvare: 1.0.2.46) and cannot get decent speeds. I have 100 Mbps from ISP, but can get 20 max to any wireless device. I don't have a lot connected (2.4G: Google Hub, Google mini, Nest Protect, Chromecast & 5G: Win10 (Nighthawk AC1900 USB Adapter), Pixel 2, Macbook Pro, Shield TV). I've checked the router is getting a good speedtest in the QOS menu (~110 down & ~10 up) and it's connected to a CM500 modem. I've checked the channel, and there's only one other device nearby on the same channel (44).

I like to use Nvidia Gamestream from my PC to Shield TV and get bandwidth (4Mbps req., 12Mbps recom.) and jitter errors (40ms req. 10ms recom) when trying to play. I have tried hooking up ethernet to shield tv and the errors go away.