Ipsec no return traffic

Hi there,

I'm a little lost here. I was able to connect to VPN locations before.

The firewalls are version 5.2. just standard ipsec, nothing fancy.

The only thing had changed -> Client OS from Windows 7 to 10.

Forticlient upgrade -> 5.4.

Now I'm still able to connect, VPN status shows "connected" but Bytes sent shows data and Bytes Received shows 0.

And I can't connect to private remote ip addresses.

When I start debug on the firewall the Ike auth goes fine but shows every time "Hello R U there acks"

I've disabled the Windows  firewall. Downgraded the client, reboot the FG firewall etc. no success at all. :(

Best,

E