Traffic Graph counts untagged traffic

[JamesFrisch]

Strangely, all traffic that is generated, counts against the untagged traffic in my traffic Graph on the dashboard.

Untagged traffic is only used for DHCP for newly plugged in devices. There is currently no device in the untagged group, there are no firewall rules for this interface. Even WAN has its own VLAN. OPnsense is router-on-a-stick, is that maybe a reason?

It does not bother me, I am just curious to why this is the case.

Picture 1: Dark blue is the untagged traffic, bright blue is WAN.
Picture 2: Around 10 VLANS, all the traffic added together equals untagged.

The same strange behaviour is true for Interface Statistics.

[JamesFrisch]

Any ideas why this happens? Do I have a thinking error?

[Patrick M. Hausen]

Traffic on the parent interface counts all packets on that interface tagged or not. It's generally advised not to use untagged on a trunk port, i.e. a port that carries tagged VLANs.

[JamesFrisch]

That was my thinking error! I thought of VLANs a separate interfaces instead of untagged as parent interface. Thank you for the clarification!