Versions 4.0 and 4.1 do not let you monitor the int0 interface when you have the XL card installed.
This is because the XL card is an accelerator card that needs a special driver and kernel for monitoring. When the XL card is installed the system will detects it's presence and automatically load that special driver and use the special kernel settings. The special driver and settings won't work for int0.
Now if you want to monitor with int0 and not the int2 or int3 interfaces, then there is an option with version 4.0 and 4.1. You can physically remove the XL card, and the sensor will detect the removal and load the standard driver and use the standard kernel settings and the int0 interface can then be monitored just like with a standard IDS-4250-TX box.
Because of requests like yours, this was changed in version 5.0 (and 5.1). The interface drivers and kernel settings were consolidated for the standard TX interfaces and the special XL interfaces. So in version 5.0 you can now monitor the standard copper ethernet as well as the XL interfaces at the same time.
But do be aware that the performance gains when using the interfaces on the XL card will not be seen for monitoring on the copper ethernet interface of the main board. The acceleration is built directly into the fiber ethernet ports themselves.
