When disconnect a PC on External side Internal network can still ping destination.
When I test every basic configuration and the problem persist, the idea was put Electrical transceiver to receive traffic instead of SRU RJ45 port.
When use electrical transceiver on LPU the traffic was restablish completly.
First I thing i was problem for DPI system (IPS, and FW).
The analysis start on IPS (USG5360) verifying the configuration and alarms.
Restore the backup configuration until the equipment was working fine but nothing rare.
The decision was to verify first one by one equipment until only NE40 keeps alone to C vendor devices.
Not use RJ45 on SRU port for traffic although it looks like support the same feautures as normal port.