Each net a.b.c.d/n defines a net address with d=min ( least significant 32-n bits = 0 ) and broadcast address with d=max ( least significant 32-n bits = 1 ), which can’t be used as client IPs.
The net 192.168.0.24/31 has net address 192.168.0.24 and broadcast address 192.168.0.25.
The net 192.168…0.24/30 ( net address 192.168.0.24, broadcast address 192.168.0.27 ) gives the client IPs 192.168.0.25 and 192.168.0.26.