Steps to reproduce:

1. Use the latest "Linux by zabbix agent (active)" template
2. Have kvm based vms running on the host
3. Have vnet interfaces discovered
4. Verify the link speed

Result:

Kernel always reports link speed of 10mbit for any vnet* devices related to kvm virtual machines, so the speed related trigger is fired.

Someone reported this on the forum:

https://www.zabbix.com/forum/zabbix-help/359479-centos-kvm-incorrect-speed-for-vnet-interfaces

See:

https://access.redhat.com/solutions/65061

Quote: "vnet interfaces are tap devices. The 10Mbps is just a cosmetic figure in a tap device's virtual firmware. This speed has no bearing on the speed of a guest's virtual device whatsoever."

Expected:
vnet devices should likely be excluded in the default regex for {$NET.IF.IFNAME.NOT_MATCHES}