When all interfaces plugged in, router crashes (AC-RT66U) - can't ping GW/access GUI

[asus_user]

I was running Merlin 3.0.0.4_374.35_4 and just upgraded to 374.39_0 to see if that fixed it to no avail.

Here are the symptoms:

I was previously just using one wired LAN connection and one wired WAN to my cable modem. Everything else in my small condo uses wireless (android phones/tablets/iphone/macbook/rokus/samsung Smart TV, etc).

I just built out a new home lab this afternoon comprising of two more desktops, one with an additional NIC card that I intend to ultimately setup in promiscuous mode, but has not yet been altered.

So now I have all four LAN interfaces occupied, but the other two desktops are powered down. Because they are still plugged in, there's power to their NICs, so my link lights are lit up on the Asus

Just to reiterate, I only have one powered-up system utilizing a physical connection at this point (my original desktop, unaltered in configuration)

As soon as the other interfaces are connected (even unpowered), I can ping my router GW a few more times and then it just dies. My system is Ubuntu 13.10 using a static IP outside of my DHCP range, and a restart of the network service does not help. I've tried switching it back to DHCP, but it doesn't work. If I unplug the physical interface and plug it back in, I might get a couple of ping responses, but by the time I try to pull up the web gui, I'm presented with the message

"changes have been made to the IP address or port number. You will now be disconnected from the RT-AC66U. To access the settings of the RT-AC66U, reconnect to the wireless network and use an updated IP address and port number"​

I rebooted the router multiple times, and the same behavior persisted each time. I swapped out my ethernet cable, and I tried using different ports on both my desktop (two interfaces) and the router. Each time, as soon as I plugged in the additional network cables, the thing fell apart and couldn't even be pinged.

This thing had been running pretty great for me for well over a year, but I always only utilized a single physical interface at once. Having to purchase a replacement $200 router or augment this with a new gigabit switch will really suck...

Anyone had similar issues? I googled that message and saw lots of people getting it, but none of them appeared to have the same symptoms as me.

 

[asus_user]

A quick follow-up. I have narrowed it down to where it only seems to happen when I have one specific NIC plugged in on one of my desktops (even when powered off). The NIC is a Marvell Yukon Gigabit onboard an ASUS motherboard from the 2008 era (P5E something I think). I see no errors on the Asus router's system logs, but clearly the NIC is sending out something that's breaking my network when plugged in.

Looks like I may end up having to buy another NIC card for that server.. just seems odd.

 

[TonyH]

Hi,
Just curious, all your NICs are on latest driver? Any funnies on advanced setting on the card? I always have good luck with RealteK card on Linux(Ubuntu, Mint both latest release)

 

[Marinemaster]

Check cables, swap see if it makes a difference.

 

[asus_user]

Hi,
Just curious, all your NICs are on latest driver? Any funnies on advanced setting on the card? I always have good luck with RealteK card on Linux(Ubuntu, Mint both latest release)

What's interesting is that the system causing the issue isn't even powered up. It's plugged in (meaning the mobo is supplying minimal power to the NIC for a WOL config), but motherboard hasn't been powered on and no OS is running. I tried looking for firmware that could be applied Out of Band from the bios or operating system, but none exists