p2p port forwarding problem

Hi,
I have a problem with p2p port forwarding.
I want to open a port for p2p traffic.
Client are connected to the network through routerboard 411
PPPoE server is a routeros on PC. NAT active.
The authentication is managed by radius server that assign a private address to the client.

This is my situation: (example IP)
PPPoE public ip: 10.0.0.1
PPPoE private ip: 172.0.0.1
Client ip assigned from radius server : 172.0.0.2
Customer’s mikrotik ip: 192.168.168.1
Customer’s pc where I have to forward port: 192.168.168.2

My firewall rules follow:
On pppoe:
1
chain=dstnat action=dst-nat to-addresses=172.0.0.2 to-ports=31000
protocol=tcp dst-address=10.0.0.1 dst-port=31000

2 chain=dstnat action=dst-nat to-addresses=172.0.0.2 to-ports=31000
protocol=udp dst-address=10.0.0.1 dst-port=31000

On customer’s mikrotik

1 chain=dstnat action=dst-nat to-addresses=192.168.168.2 to-ports=31000
protocol=tcp dst-address=10.0.0.1 dst-port=31000
2 chain=dstnat action=dst-nat to-addresses=192.168.168.2 to-ports=31000
protocol=udp dst-address=10.0.0.1 dst-port=31000

I think that this configuration is right but p2p client has reconised the ports correctly open only for little time and now the p2p client don’t reconised such ports anymore.

I hope , you can help me because I’m in big trouble.

Thanks and best regards

Edoardo Potenza