Interface Monitoring

[msquare]

I am new to this forum and looking for some help with interface monitoring.
We are not able to get interface status monitored through Zabbix it shows below error:

Cannot evaluate function last(/MaDRtR.PfSense/vfs.file.contents["/sys/class/net/em0/operstate"]): item is not supported.

I did check Dev folder but unable to figure out correct path for it. Please can someone help here. The interface speed is working fine.
Trigger expression from Zabbix:

Problem: {$IFCONTROL:"em0"}=1 and last(/PfSense/vfs.file.contents["/sys/class/net/em0/operstate"])=2 and (last(/PfSense/vfs.file.contents["/sys/class/net/em0/operstate"],#1)<>last(/PfSense/vfs.file.contents["/sys/class/net/em0/operstate"],#2))
Recovery: last(/PfSense/vfs.file.contents["/sys/class/net/em0/operstate"])<>2 or {$IFCONTROL:"em0"}=0

Does anyone knows about the correct path for WAN interfaces in Pfsense.

[msquare]

Any help with this issue. I see FreeBSD template dont have network discovery in it. Is there any way to monitor pfsense interfaces.