In VPN Concentrator,PPTP VPN connection, not get authentication, verifying user name & password, but when we connect through vpn client software, which is IPSEC/UDP, get connect on VPN concentrator, this happens suddenly. after some time it woking. so, we contucted a test from outside of the network, PPTP VPN is working, while comes from ISP is not. what could be cause.
prompt response is much appicate,
thanks & regards