AT&T Fiber (Internet 1000 Service) - Orbi WiFi download speed <100Mbps while AT&T NVG599 > 300Mbps

I enabled the Orbi WiFi again, signed on to the RBR50 via my web browser (orbilogin) and reviewed the WMM setting.  The option "Enable WMM (Wi-Fi multimedia) settings" was "checked" (on).

As you may know, within orbilogin there is an option to run an OOKLA speedtest (under the Advanced tab).  I did that and got back 495.55 Mbs download. Seems the RBR50 was getting a good download speed via AT&T Fiber.

I then ran an OOKLA web based speed test from my Macbook Pro and got around 65 Mbs download (much slower). (I'm was connected to the Orbi WiFi via 5GHz, 80 MHz).

I returned to orbilogin and, under the Advanced Wireless Settings, turned off (unchecked) the "Enable 20/40 MHz Coexistence" option.  Saved that change and rebooted the device.

Upon reboot, I ran another OOKLA test via orbilogin (got back 495 Mbs download again) and then ran an OOKLA web based speed test from my Macbook Pro and got back 493.96 Mbps (still connected via 5 GHz, 80 MHz).  I was pleased for about 5 minutes.  I ran another web based OOKLA speed test and the download speed was back to 69.5 Mbps.  

Back in orbilogin, I could see that my macbook pro was connected to one of the Orbi satellites (vs. the Orbi router).  For a test, I turned off (unplugged) both of the Orbi satellites and rebooted the Orbi router.  After the reboot, I verified my macbook pro was connected (5GHz, 80 MHz) and ran another OOKLA web based speed test.  The results were back to 496 Mbs.   I waited about another 5 minutes and ran the test again – and the results were about the same, 495 Mbs download speed.

I decided to power-up one of the Orbi satellites and followed the Orbi sync procedures.  

and then watched to see if my macBook pro would connect to it (or remain connected to the Orbi Router).  At first, the MBP stayed connected to the Orbi Router -- after a while it switched to the Orbi satellite.  I ran another web based OOKLA speed test and at the beginning of the test, the speed was well below 100 Mbs but as the test progressed, it ramped up to over 400 Mbps (at the very tail end of the test) - I went back to see which Orbi device my MBP was connected to and guess what, it was back on the Orbi Router.  

This makes me a bit suspicious that the Orbi satellite is a part of the problem (or the Netgear Orbi software has a bug somewhere). 

So, this isn't fully resolved for me yet - I'm going to do a bit more monitoring (watching the speed) BUT I really don't plan on spending more hours running tests, making configuration changes and rebooting the Orbi devices - at some point, if a fix doesn't "stick," I'll just move on to another vendor.