I am experiencing a strange issue on my RT N16 which runs the recent tomato release. Sometimes on my custom created vlans connectivity drops: DHCP ip don't get assigned, if static client ip is used ping requests get dropped and few packets pass through. Its very strange becuase when I insert another cable into vlan port it works. But if I put the original cable into br0 network ports it works fine. Once it hapened on the vlan which connects to access points. The access points of Linksys and another company stopped working, at the same time RUKUS access points, which were on the same network, worked fine. I used a cable to connect my test pc to that network and it worked. With regard to faling access points, the network availability is shown, but, as tomato won't assign dhcp ip, the clients don't get connected. I want to find out why it is happening. Which tools I can use to diagnose the issue?
I did some tests using a linux machine by connecting it to malfunctioning vlan network. When I used 'mtr' tool from the linux box to traceroute + ping the routers vlan interface, the best was 0.6 and the worst was 215. The replies from the normal functioning br0 interface was: best 0.6 worst 0.6. If I just ping the vlan interface, the replies are not uniform: the normal time is around 0.240 MS but certain packets take 145 MS or above. In many cases there was huge packet loss. Does this mean that there is a hardware failure in the Ethernet ports of the router? At present the two ethernet port, which were bound to the vlans, show the above mentioned symptoms. Only the ports bound to br0 are working fine.