How to make 253 OpenVPN clients

Server config:
TAP
Client address pool: 192.168.1.2-192.168.1.254

On client sides:
A router with OpenVPN client embedded. Disable the LAN DHCP so that PC can get IP from VPN server instead of OpenVPN client.
VPN server-->VPN client-->PC
L-->VPN client-->PC
L-->VPN client-->PC
L-->VPN client-->PC
L-->VPN client-->PC

Expected result:
Only PC can be assigned an IP from VPN server, VPN client won't be assigned an IP, so max...

How to make 253 OpenVPN clients