RBR/RBS50 WiFi Issue (speeds drastically drop after one to two weeks)

[Bambler]

I have an old RBR/RBS50 setup that I purchased new many years ago. It's working fine for the most part, but it's starting to act weird recently.

Normally, I get WiFi speeds of around 250 Mbps, which is good enough for me, but after a few weeks it will bog down to 25 Mbps on both the base and satellite. Wired speeds to devices connected directly to the RBR50 remain at my 1 Gbps WAN speed.

Rebooting the RBR fixes this issue and it goes back up to 250 Mbps, but again, it's like clockwork in that after one or two weeks, it will start to bog down again.

1. The RBR is acting as an Access Point with my ATT BGW320 acting as the router.
2. I'm still running the last firmware that was remotely given via the ORBI app. I haven't manually updated. However, this issue only recently started occurring so the existing firmware was acting fine for years.
3. I have 60+ devices, which is more than what it recommends I know, but they're not all talking at the same time and again, I've had this for a long time without issue.

Any ideas what's wrong?

[Bambler]

I found this thread that mirrored the issues I’m having. https://community.netgear.com/t5/Orbi-Wi-Fi-5-AC-and-Orbi-with/Orbi-WiFi-speeds-drop-low-until-I-reb...

Anyone familiar with this issue?  Anyone have any tips on pinpointing the device causing it?

[FURRYe38]

What Firmware version is currently loaded?
Be sure your using a good quality LAN cable between the modem and router. CAT6 is recommended. 

How are you speed testing? Wired or wireless? Wired is preferred.

How many RBS are deployed? 
What is the size of your home? Sq Ft?
What is the distance between the router 📡 and satellite(s)🛰️? 30 feet or more is recommended in between RBR 📡 and RBS 🛰️ to begin with depending upon building materials when wired or wirelessly connected.
https://kb.netgear.com/31029/Where-should-I-place-my-Orbi-satellite ‌‌🛰

Does this happen with the RBS turned OFF? 
Does this happen with both wireless and wired devices? 
What channel configurations are currently set on the router?

Does this happen with all but a few wifi and wired devices connected to the system? 60+ device could be something bogging the system down.

Be sure to disable any MAC Address randomizers on phones and pads while at home:
https://community.netgear.com/t5/Orbi-App/NETGEAR-Mobile-Applications-and-Apple-Devices-FAQ/td-p/222...

Try disabling the following and see:
Armor, Smart Parental Controls or Circle, Traffic Meter.

Has a factory reset and setup from scratch been performed since last FW update?