HORRIBLE wifi speed but ULTRAFAST via ethernet ports

Issue:

Cable modem (SPECTRUM) delivering 350+ Mbps INBOUND with near equal throughput (measured via FAST.COM) to devices via Ethernet ports on two satellites.

Wifi throughput, HOWEVER, typically begins with a long delay at 0Mbps before:
- starting in Kbps and meandering around that range to settle in Kbps
- starting in Kbps and bouncing chaotically up and down over the course of about a minute in the 2 to 8 Mbps range before settling back down to anywhere from Kbps to 8 Mbps range.

Sometimes rebooting improves responsiveness at the beginning of the test and yields anywhere from 50 to 150 Mbps. However, by the next day or so performance degrades back to utterly pathetic as outlined above.

ORBI HARDWARE - distributed in somewhat of hub arrangement
Daisy Chain OFF – Guest Network OFF
RBR50
2 RBS50
RBS40V (no Alexa)

RBS50 #1 and RBS40V are at least 30 feet from RBR50
RBS50 #2 is 24 feet from RBR50 – it can’t be any further away.
Wifi Backhual to RBR50 = GOOD ON ALL

16 connected devices allowed via ACCESS CONTROL and none of which are configured in a NETWORK LOOP

DEVICES CONNECTED DIRECTLY TO RBR50 via POE SWITCH OUTPUT
3 POE cameras
1 Ooma phone


DEVICES CONNECTED VIA ETHERNET PORTS ON SATELLITES at 350+ Mbps
RBS50 #1 - iMac
RBS50 #2 - iMac, MSI laptop, LG#1 TV
RBS40V - 1 non POE camera

DEVICES CONNECTED VIA WIFI
1 LG#2 and 2 VIZIO TV’s
iPhone #1           
iPhone #2
iPad #1
iPad #2

What Firmware version is currently loaded?
RBR50 AND RBS50 2.7.4.24
RBS40V 2.6.2.8

What is the Mfr and model# of the Internet Service Providers modem/ONT the NG router is connected to?
DOCSIS EU2251

What is the size of your home? Sq Ft?
1700

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?

Channels set to 10 (it was the empty channel via Wifi Commander at the time) and 36 (empty as well)
Wifi Commander shows my network producing 4 named radio frequencies and 1 mac address frequency.
2.4Ghz signal strength varies from -24 to -50
5G varies from -38 to -62

There are approximately 8 local systems with signals anywhere from -60 to -85 (some stable on a channel and others roaming)

Try enabling Beamforming and MIMO(MIMO may or may not be needed) and WMM. Under Advanced Tab/Advanced Settings/Wireless Settings
Enabled

Try disabling the following and see:
Armor, Circle, Daisy Chain, Fast Roaming, IPv6 and Set 20/40Mhz Coexistence to 40Mhz only. Set Short preamble instead of Long preamble modes. Save settings and reboot the router and satellite(s).

Disable ARMOR – NO IMPROVEMENT
Daisy Chain – set to OFF
Fast Roaming – deselected
IPv6 - disabled
20/40 Mhz – deselected (There is no 40Mhz only setting)
Setting PREAMBLE to SHORT or LONG did not improve things so I reset to Auto