Device not responding to sysupTime

[gibru]

I'am trying to graph a NetWall device.
Unfortunately this device does not respond to sysupTime.
I have 40 devices configured, and only this one has this behavior.
I know the possibility to change settings->poller->Downed host detection to ping. But this setting is for all devices. It is not possible to change it per device.
What udp port does cacti use for UDP Ping ? Many of my devices are FireWAlls and i need to create rules for it.
In a future release it should be useful to choose for each device the oid to poll for Down detection with sysupTime as default value. The choice of SNMP /Ping could also be per device.
If there's another work around please let me know.
Thank you for your help.

[gibru]

Cacti ver 0.8.6.d
I found in ping.php that port for UDP ping is 33439. (line 218)
Is it possible to change it with $this->host["snmp_port"] to use the same port configured in firewall for polling snmp.
So i can use udp ping for all devices and the port configured for SNMP.
NetWall use port 4010 for snmp, checkpoint port 260.
Thank you for your opinion.