WiFi Slow after 2-3 days until reboot?

I'm really at my wits end fighting with this Orbi System. I've read all the relevant forum posts I could find and am still struggling.

I have 200 Mb/s service from Xfinity. Orbi RBR50 is connected to a CM700 modem. Firmware is 2.3.5.30. Satellite is ~30 ft away from the router. Security is WPA2-PSK [AES] only.

All is great with my wired connections, I always get the full 200 Mb/s.

When things are running well I get consistent 180+ Mb/s WiFi speeds.

About every 2-3 days though, WiFi speeds drop to ~40 Mb/s on all my WiFi devices... even when on 5G right next to the router.

When the slowdown occurs, wired devices remain consistent at ~200 Mb/s.

After a reboot, WiFi speeds instantly return to ~180 Mb/s

I've tried a "hard reset" of the both the satellite and main Orbi.

I've tinkered with the channel settings... I have very little interance from neighbors.

I've tried tinkering with all the advanced options - Daisy Chain, MIMO, Beam forming, 20/40 coexistence, etc.

None of this has worked... like clockwork after 2-3 days it's back to "slow mode" of only 40 Mb/s... and after a reboot jumps right back to 180 Mb/s.

I'm capturing the logs (attached)... nothing looks remarkable?

We have the usual assortment of connected home devices -- 3 apple tv, 1 roku, 2 ring cams, 4 amazon echos, 4 ipads, 2 iphones, imac, 2 pc laptops, wink hub, 2 yamaha AVRs, Rachio, HP printer, 1 google home, sony bluray player, comcast DVR...

I'm out of ideas... and really frustrated with this Orbi system.

Help?