What Firmware is currently loaded?
What is the Mfr and model# of the ISP modem the NG router is connected too?
What WiFi devices are you using to speed test. Some WiFi devices maybe maxed out or limited by there design. Most current devices should see any where from 400-500Mpbs depending upong connection rate.
What connection rate is the wifi devices connected? Use WiFi Sweet Spots on your mobile device to see the connetion rate.
Ensure your device is connected to 5Ghz instead of 2.4Ghz.
What is the size of your home? Sq Ft?
What is the distance between the router and satellite(s)? 30 feet is recommended in between RBR and RBS to begin with depending upon building materials when wirelessly connected. https://kb.netgear.com/000036466/How-far-should-I-place-my-Orbi-satellite-from-my-Orbi-router
What channels are you using? Auto? Try setting manual channel 1, 6 or 11 on 2.4Ghz and any unused channel on 5Ghz.
Any Wifi Neighbors near by? If so, how many?
Try enabling Beamforming and MIMO(MIMO may or maynot be needed) and WMM. Under Advanced Tab/Advanced Settings/Wireless Settings
Try disabling the following and see:
Armor, Circle, Daisy Chain, Fast Roaming, IPv6 and Set 20/40Mhz Coexistence to 40Mhz only. Save settings and reboot the router and satellite(s).
