OpenVPN ping pfsense on LAN, but not ping another computer
I'm having a really problem with my pfsense. I setted up OpenVPN Server and i got connect but when i ping pfsense server it works and when i try ping AD Server not working. I Setted up fix public IP on WAN, i setted up fix IP on LAN but subnet mask is different than VPN client IP mask. So i tried setted up another subnet mask on LAN but it's reporting me an error saying "The IPv4 address 10.5.XXX.000/24(old config was 10.5.XXX.000/16) is being used by or overlapped with: OPT1" but i dont know why this happening.
I dont know if subnet mask is the really problem, cause on pfsense the subnet mask on lan is 10.5.xxx.000/16 and the ping works for pfsense. (PS: I Setted up and allowed Firewall Rules -> OpenVPN tab)
(PS2: I Shared a folder on AD Server to enable ping and firewall ports, it supposed to work and ping AD Server with no problems)
(PS3: my config is AD Server as a DNS and DHCP Server, so it setted up as "DHCP Relay").