Openserver 5.0.4 can't be ping or telnet into from a remote site

Hi,

Can anybody help me out why l can't not ping my server with Openserver 5.0.4 with my windows machine from a remote site.
The machine could see the local LAN with the Router however, i can't ping or telnet unto the server from another site on the WAN. The default gateway was configure on the Openserver under the Advanced option but it didn't work.
Can anybody assist me on this?

Thanks

Kayode