Netgear XR500 Unnamed devices poping up

There are no secrets on a MAC address...

The ones with an OUI starting with 02:xx:xx (like any x2:.., x6:... xA:..., or xE:... are local managed MAC, not assigned to a vendor, freely usable, just unique on a LAN, used by VMs, wireless access points offering multiple SSIDs/VLANs. Look there  -> https://en.wikipedia.org/wiki/MAC_address#Universal_vs._local

For the other random ones, say thank you generation tin hat, say thank you Apple (-> Use private Wi-Fi addresses in iOS 14, iPadOS 14, and watchOS 7 [with complete ridiculous enforced defaults!]), say thank you Android (-> Privacy: MAC Randomization [with smart defaults of course]).

Needless to say - there is no reason to randomize MAC addresses on a home, private, or business network. A correct hardware MAC key for access control, base line security, .... So disable this **** on the network connection settings (by each SSID).

So we can blame Netgear for many things - regardlss on how many times you factory reset your router. Can't see a Netgear problem here...

PS. For those hyping Apple for a "great" privacy innovation - Android has this feature  since Android 8.0 Oreo (API 26, August 2017) - and it never caused (m)any issues.