Orbi 850 + nighthawk pro mr5100 modem = SLOW. Help!

[bariumslinger]

I am using an orbi 850 router plus 1 orbi satellite to supply wifi to my home. Modem is a Nighthawk hotspot pro (mr5100) connected to the WAN port on the router via the netgear supplied ethernet cable. When the hotspot was broadcasting wifi, I would routinely see dl speeds of around 100 Mbps. When connected to the orbi router, DL speeds using orbi wifi (hotspot wifi disabled) are anywhere from 15-40Mbps, almost always closer to 15. Upload speeds have remained about the same (around 10Mbps). I have confirmed the latest firmware for modem, router, and satellite. I have rebooted everything (more than once). I set up the modem the following way: turned ON IP passthrough, turned OFF DHCP, and DISABLED ethernet standby. 

I don't know if it is a settings problem in my modem or in the orbi. Any suggestions?? Wifi coverage with orbi is great, as you'd expect, but dl speeds are a real disappointment. Any ideas would be most helpful.

Thanks.

[FURRYe38]

Netgear has set up a community forum specifically for the Orbi AX (WiFi 6) products. Most of the people who watch that forum are more likely to have experience with Orbi AX and know how to work it better than those of us who follow this "general Orbi" forum. Might be more likely to find someone who has a solution if the question is posted there:
https://community.netgear.com/t5/Orbi-AX/bd-p/en-home-orbi-ax

Please use this link to the main forum product list to review and choose where to make your posts.
https://community.netgear.com/t5/NETGEAR-Forum/ct-p/en-netgear

Thank you.