cax80 LAN Setup IP Subnet Mask

Greetings

CAX80 Nighthawk router

Advanced tab

Setup

LAN Setup

IP Subnet Mask

I would like to limit the number of devices that can connect to the DHCP to less than 62. Setting the IP Subnet Mask to 255.255.255.192 should allow IP numbers from x.x.x.2 through x.x.x.62.

The cax80 will not accept 255.255.255.192 subnet mask. It will only accept 255.255.255.0 and 255.255.255.128.

I have assigned fixed IP's 10.1.1.2 through 10.1.1.20 the remainder 10.1.1.21 through 10.1.1.62 can be assigned dynamically.

I know that using 255.255.255.0 and setting the range to 10.1.1.2 through 10.1.1.62 essentially accomplishes my goals. What I want to know is why the cax80 IP Subnet Mask cannot be set to 255.255.255.192.