IP Networking

First of all, hello.
I have a problem installing a vpn server and client.

My server is a computer running windows 7, and windows, running a virtual machine running debian.

In the debian system, I've the vpn server installed (SoftEther VPN Server)

The problems come when I try to connect to the vpn server using L2PT/IPSec protocols (using for example, my android device). And then, when running another virtual machine that interacts as client, I get this error: <Error code 1: Connection to the server failed. Check network connection and make sure that address and port number of destination server are correct.>

What do I need to add to my iptables to solve it (allow L2PT/IPSec connections and solve the error code 1)?

This is my firewall configuration, that is currently "disabling" the firewall.

Code:

#! /bin/sh 
# 
#  
# 
# 
 
#  Flush tables
 
iptables -F 
iptables -X 
iptables -t nat -F 
iptables -t nat -X 
iptables -t mangle -F 
iptables -t mangle -X 
 
# Default policy
 
iptables -P INPUT ACCEPT 
iptables -P OUTPUT DROP
iptables -P FORWARD ACCEPT

Then, I have another problem. My router doesn't allow SecureNAT that gives you the SoftEther's VPN Server, so I have it disabled, but I need to have nat on the devices connected to the VPN Server, that have an ip assigned by the server using dhcp protocol.
This ips have the range of 192.168.30.10 until 192.168.30.50.

Do I need to add new rules to my iptables? What rules?

Thank you in advance.

Moderator's Comments:

Please use CODE tags (not QUOTE tags) to display sample input, output, and code segments.

Your default firewall behaviour for all outbound traffic is to DROP. Are you sure that's what you wanted?

Check you can actually connect to the right port by running telnet <port number> and seeing if you get a connection.

The VPN server needs to be able to allocate an IP address for the client, is the VPN server running a DHCP server? If not, have you allocated a pool of addresses to the VPN server?