Port forwarding not working - tcpdump receives packets

Hi, I am trying to set up port forwarding for UDP 6000-6009 on my Archer C7 runnning OpenWrt 18.06.2 r7676-cddd7b4c77 / LuCI openwrt-18.06 branch. However, when testing using https://www.ipfingerprints.com/portscan.php, the ports are shown as closed (I've selected UDP scan). In terms of troubleshooting, tcpdump -pnvvi eth0.2 port 6000 does show the received packets, so it seems as though my ISP isn't blocking it.

I've set up the port forwards via the GUI (Network > Firewall > Port Forwards) and am stuck with how to resolve this issue. Any assistance is greatly appreciated.

Don't trust blindly these internet scanners.
Does it work for you or not?
You can verify that the packet is forwarded by running the tcpdump in the inside interface.


Also, even if your router receives and forwards the packets correctly, the destination host must also be configured to receive them.

Good points, I did make sure the internal firewall on the host was off, and used netcat to listen on that port. But I'll give it a try without using the port scanner - could try from a machine outside the network