Zyxel GS1200-5HP v2 does not forward traffic within the same VLAN

jtk

I have the VLAN configuration above (for ports 03 and 04 there are no other active VLANs). For some reason the switch does not forward packets between ports 03 and 04, but traffic to port 05 (the trunk port towards the firewall/router with the gateway ip of the VLAN) works.

Any ideas on how to allow traffic within the same VLAN on the switch?

There is no link aggregation used.

PeterUK

Maybe the devices on ports 3 and 4 have a firewall

jtk

No. I can ssh both of them from a different VLAN, while connection comes from the router via the trunk port 5. But I cannot ssh, ping or anything from each other.

PeterUK

Can you Wireshark on one device then ping from the other device to the one doing the Wireshark with filter

icmp or arp

You should see a broadcast ARP with who has IP seen by any the one running the Wireshark and IP of that is as this MAC in reply

The other reason could be that one or both devices use subnet 255.255.255.255