Same DHCP address for VPN connections with open VPN?

[zo718]

I set up an open VPN server in my PFSense and as an IPV4 tunnel network, I have 172.16.250.0/24.

When multiple users (6 or more) connect to VPN most of them get the same IP addresses. either 172.16.250.2 or .3 .4 but nothing more.
I haven't been able to figure out where the DHCP settings for the Open VPN server is located.
Is this a normal behavior?
How do I fix this?

Thank you.