VPN IP phone

Hi,
My config on what I call the LAN subnet:

Main router TPLINK OpenWrt Chaos Calmer 15.05
Switch Cisco L3
Current Asterisk Version: 11.23.0
Freepbx FreePBX 13.0.192.19

And a REMOTE subnet where I try to install a S700 sangoma ip phone.

First I installed an openvpn server on the openwrt main router with subnet 10.10.0.0
listening to 1200 instead of 1194 and a VPN client on a PC in the REMOTE subnet

On the main router in the LAN subnet:
[email protected] /root [#] netstat -ltnup | grep openvpn
udp 0 0 0.0.0.0:1200 0.0.0.0:* 30791/openvpn
[email protected] /root [#] ifconfig tun0
tun0 Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
inet addr:10.10.0.1 P-t-P:10.10.0.2 Mask:255.255.255.255
UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1
RX packets:91252 errors:0 dropped:0 overruns:0 frame:0
TX packets:96402 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100
RX bytes:7102473 (6.7 MiB) TX bytes:89067329 (84.9 MiB)

My openvpn Works like a charm. I can ping the IP’s subnet LAN from the REMOTE subnet.

I’d autoprovision the S700 in the LAN subnet without VPN server running. The account was registered. Then I start the VPN server on the freepbx server (system Admin / VPN server enable / add client / add that client in the extension for the s700 / save rebuild update phone). ‘VPN activated’ appeared on the ip phone screen

Clientxxx.conf seems to be ok:

Generated at: Wed, 10 Jan 2018 00:03:59 +0000

client
dev tun
proto udp
resolv-retry 60
nobind
persist-key
persist-tun
remote-cert-tls server
ca sysadmin_ca.crt
cert sysadmin_client0.crt
key sysadmin_client0.key
comp-lzo
verb 3
remote WAN_IPADDRESS_OPENWRT 1194

I configure a redirection for port 1194 to IP_ADDRESS FREEPBX server
config redirect
option target 'DNAT’
option src 'wan’
option dest 'lan’
option proto 'udp’
option name 'FreePBX VPN Server’
option dest_ip '10.66.0.2’
option dest_port ‘1194’

And now the account isn’t registered on the ip phone.

How can I debug this problem.
Thanks for your time helping out.
Laurent