RBR50 started assigning 192.168.10.x instead of 192.168.0.x to Apple devices

I have been using a Netgear Orbi RBR50 for many years, and it's worked well.  I've configured my internal network (wired and wifi) to assign addresses of 192.168.0.x (third digit zero), with many address reservations set up.

In the past week or so, the DHCP server has been sending IP addresses of 192.168.10.x (with router IP 192.168.10.1), i.e. third digit ten, to some of my wifi Apple devices.  ONLY to Apple devices!  Needless to say, those devices don't work on wifi when this happens.  It has this problem even if I set up an address reservation linked to the Apple device MAC address.  The only way I can get the affected Apple devices to work is to manually configure my wifi IP address and put in both the correct 192.168.0.x IP and the 192.168.0.1 router IP.

Does anybody have any idea why this is happening and how I might go about fixing it, other than being forced to manually configure IP & router on my Apple devices?

Thanks,

John Feinberg