WLAN backhaul incorrect

Thanks for attaching the screen shot.  This appears to indicate that even though the physical distance between router and satellite is only 5 meters, the WiFi link is  operating at 573Mbps (i.e. horribly show)

The most common reason for this would be building material between the two units, such a concrete floor.

It might be worth confirming that the satellite "works" by temporarily relocating it to the same room as the router. (Good thing Orbi satellites are portable!)  If the satellite is placed in the same room and powered up, the WiFi backhaul link should be very close to the published rate. (2400Mbps).

There is one other potential issue: interference from Weather or Military Radar.

Netgear does not appear to have included Factory Settings in the 760 User Manual (sigh), but the settings for the 750 product are:

In many parts of the world,  WiFi channel 108 is in the frequencies called DFS/TCP  (see footnotes)

https://en.wikipedia.org/wiki/List_of_WLAN_channels#5_GHz_(802.11a/h/n/ac/ax/be) 

I am not qualified to suggest how a person would determine whether there are any radar systems operating nearby which would trigger a reduction in Transmit Power.