ORBI RBR750 - AC4200 - Very slow speeds - would greatly appreciate any help

[rmc726]

I just bought the expensive ORBI - the AC4200 along with 2 Satellites. I have a gigabit connection and no other devices are connected to the ORBI currently. I am connected to one of the Satellites through ethernet cable and my computer is a new Dell i9 Windows 10 with 64GB RAM and an SSD. Unfortunately, I am only pulling down 78 MBps through the ORBI when I was told it would be much faster. And my Synology Diskstation NAS, which is connected to the ORBI router, is connected at about 10 MBps. Everything has been rebooted multiple times and firmware is current. Help!!!!

[FURRYe38]

What Firmware version is currently loaded?
What is the Mfr and model# of the Internet Service Providers modem/ONT the NG router is connected too?

What are the wired speed test results with a PC or laptop connected behind the RBR?

What is the size of your home? Sq Ft?
What is the distance between the router and satellite(s)? 30 feet or more 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?