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A bit of a frustrating problem I've been facing - I just don't know what's wrong.

I have a Netgear WNR2000v3 router with DD-WRT v24-sp2 (03/19/12) std installed. Everything works perfectly apart from one issue.

I have a fileserver that's plugged into one of the ethernet ports on the back of the router. The fileserver can see all network devices fine (can ping fine). The fileserver - and all over devices - can access the Internet via the eth0 interface (configured to be WAN). DD-WRT gets a WAN IP via DHCP - all fine.

Here's the interesting part. When my laptop is connected via wifi (device ath0 on the router), the laptop can see the fileserver - I can ping it fine. However, when I then plug the laptop into another ethernet port on the back of the router, it can no longer reach the fileserver! Whenever I ping, I get "No route to host" and "Host is down" messages interchangeably - even though it's actually still running fine.

I thought it might be an issue regarding the br0 interface created by default - but as far as I can see, the ethernet ports (eth1) and the wifi (ath0) are bridged as I would expect them to be. You can see the settings page showing this here.

I'm confident the subnets are the same. I should also note that when I SSH into the router (which I can do on both wifi and wired ethernet), the router can ping the fileserver fine at all times. I just can't figure out what is wrong, and am hoping someone can shed some light on this strange issue.

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Did you ever find a solution to this problem? I've got literally the exact same thing (same issue, same router, etc) and havent been able to find a damn thing – Finn Nov 24 '13 at 1:19
    
Same route, same issue. Came looking for a solution found this page. Windows Laptop can ssh into LAN IP of both my NAS and Linux PC which are hard-wired to the router. NAS cannot see Linux PC and vice versa. Oddly enough, from my Linux PC I can ssh into the DD-WRT and from there ssh into the NAS. The other way works as well. Something is effed-up – SiegeX Sep 12 '14 at 6:29

I found the solution, you need to run the following two commands to allow clients hooked up to the switch to talk to each other:

swconfig dev eth1 set enable_vlan 1
swconfig dev eth1 set apply 

Commands courtesy of tomshardware

I still don't understand:

  1. What these commands are doing
  2. Why they weren't enabled by default
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2  
This works for me as well using the latest DD-WRT firmware on my TP-Link TL-WR841ND v9. (I had to use eth0 instead of eth1 though.) – mgiuffrida Jul 19 '15 at 4:20
    
Thank you @mgiuffrida! That worked for me on my TP-Link router also! – Michael McGuire Sep 19 '15 at 1:53

I did some googling and it appears to be a bug in the DD-WRT firmware. There is talk on the DD-WRT forum that newer version a of the firmware will fix the issue. SiegeX's fix works great, one additional thing that I would do would be to add it as a startup command in the commands window so that next time your router reboots it will "fix" itself.

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