VLAN - Duplicate Pings


i have a little problem which i am unable to resolve on my own. I have the following setup:

  • A LEDE Box, name: a TP-LINK WDR3600. It has some VLANs configured.
  • It is trunked to an 24-port Switch which is manageable and has VLAN abilities
  • A Computer, which is connected to the switch.

The switch port where the computer is connected to is set to VLAN 10 untagged. The switch's management IP is located in VLAN 1. Both VLANs are configured in the LEDE Router, with firewall rules "allow any" between them.

The problem i have is: When i ping the switch from the computer, i get two duplicate responses (so, for each ICMP request i get 3 ICMP responses). The Switch IP is not set on two or more hosts, just the switch itself has this IP. I have run tcpdump on the computer, and it says that indeed, for each Ping, it gets 3 responses.

So, at first, i assumed the switch was faulty. But then, i installed and ran tcpdump on the LEDE box, and pinged the switch from the computer. To my surprise, the switch answers with one ICMP response per request only, so for now, i am thinking that there is some other error, maybe in my LEDE config.

So for now, it looks like this:

Computer creates ICMP request -> Package enters Switch on Port 7 -> Package gets tagged with VLAN ID 10 -> Package leaves Switch on Port 1, tagged -> Package enters the LEDE Box via Trunk Port, Tag 10 is removed, Tag 1 is applied -> Package leaves LEDE -> Package enters Switch on Port 1 -> Switch recognizes the package as an ICMP request for itself and creates an answer

Switch creates ICMP reply, tags it with VLAN ID 1 -> Response leaves Switch on Port 1, which is a trunk port -> Response enters LEDE on trunk port with VLAN Tag 1 -> -> 3 Packages, tagged on VLAN 10 leave the LEDE on the trunk port -> Responses enter Switch on Port 1 tagged -> Switch removes the VLAN tags -> Packages leave the switch on Port 7 untagged -> Computer receives 3 identical responses.

So i need some help with identifiying what could be, and how to fix this.

I have other switches in VLAN1, which are trunked to the switch with the duplicate responses, but they are not affected by this problem. Image a daisy-chain of VLAN trunks with the LEDE box at one end, then several switches, and the affected switch is the first one after the LEDE box.

I have attached the VLAN config of my LEDE box as shown in LuCI