inconsistent WiFi Speeds

When you do internet speed tests sometimes your displayed speed on the test is limited by the weakest link in the line of internet nodes between your computer and the remote test server, now I'm not saying this is your specific issue, but it's something to have in mind, have you tried doing these speed tests in different sites and times?

As I described in another thread, my wifi tests ran through iPerf running on a hardwired computer, to eliminate internet speed as a variable.  While speeds were fine when the client device was connected to the main Orbi unit, speed fluctuated drastically when connected through the satellite, even under very favorable conditions (client in the same room as the satellite, with no obstructions).

Exchanged it, but the replacement unit did the same thing.  Finally gave up yesterday and returned it, reluctantly.

Yes.  I saw that behavior.  It was because I had a WiFi scanner program open on the laptop I was using to do the speed testing.  Check and make sure you don't have any other programs open that are using your WiFi interface.