Networking hardware – Henry Poon's Blog

Resolving dd-wrt bug that prevented computers on a LAN with wired connection from talking/pinging/communicating with each other

hp — Tue, 06 Jan 2015 06:27:16 +0000

I just had a problem where the computers in my house that were all using a wired connection could not talk to each other. Computers on wired connections could not ping, and ping kept giving an error saying “destination host unreachable”. I found the solution in a very hard to find forum post on the dd-wrt forums.

This specific instance of the problem affects users of the dd-wrt firmware. In my case, I am using build 24461 of the firmware. The solution is to run the following commands on the router (either with ssh or telnet):

swconfig dev eth0 set enable_vlan 1
swconfig dev eth0 set apply

I’ve since put this in the startup commands that the router will execute, so these settings will stay even after a router reboot.

For some routers, it might be eth1 instead of eth0. It depends on which network interface is assigned to the WAN. This can be check in the router page under Setup > Networking.

Link to forum post: http://www.dd-wrt.com/phpBB2/viewtopic.php?t=152738&postdays=0&postorder=asc&start=0

Diagnosing the Source of Internet Connectivity Problems

hp — Thu, 30 Dec 2010 08:05:26 +0000

I created a nice little flowchart for people to diagnose their Internet connectivity problems. It’s pretty general and covers the most common problems. I tried to avoid lots of specific information since many Internet connectivity problems are not as straightforward as just following a flowchart.

I didn’t really go into specifics as to what kind of modem lights to look for because all modems are different. But they almost always will have an “Online” light. If that is off, then there is clearly a problem.

Router lights are usually just a power light, the WAN and LAN lights. If the WAN light is off, it means the router has no access to the Internet.

Each network adapter on the computer can be disabled and enabled by accessing “Network Connections” in Windows. That can be accessed by typing the name without the quotes in the address bar in any open Explorer window.

Converting a Router into a Switch

hp — Thu, 09 Sep 2010 04:14:30 +0000

By using a switch, I can get twice the bandwidth that I would have normally gotten from UBC Resnet. This is because I am getting more than one IP from Resnet instead of having the router to grab the one IP and rely on NAT for communication. Having one IP means I’d only get one computer’s worth of bandwidth split among both computers.

Warning: After doing this, I’ve lost all contact with my router even with the IP of the router changed. This is probably because my router is acting as a switch. The only way that I’ve found to access the router page is to reset the router. This is probably due to the fact that my router is a piece of junk and I don’t know if this is something consistent among all routers.

Change the IP of the router to something else that is unused in the network (I changed mine to 192.168.0.254)
Disable the DHCP client on the router
Plug the ethernet cable from the wall/modem to one of the LAN ports on the router (Don’t use the WAN port anymore)
Plug ethernet cables from each computer to any free LAN port on the router
Release/renew IP’s on all computers

Note: Do not use the WAN port since the DHCP functionality has been disabled.

Despite the drawback of not being able to access the router afterward, I now have all my computers networked. Some people on forums had solutions on retaining access to the router, but those methods didn’t work for me.

USB Storage over the Network

hp — Tue, 11 May 2010 06:24:18 +0000

My router (DGL-4500) comes with a USB port at the back, which implies that it can be used for plugging in an external hard drive. All I had to do was update my router to the latest firmware (that’s why I had my previous post) so that I would see the “USB Settings” page within my router configuration page. I used D-Link’s Shareport program to share a USB External Hard Drive over the network. I left the setting within the router page to use Shareport. I installed the Shareport client on my computer and I was able to access my external hard drive quite easily. However, it does take a little extra time for the computer to recognize it’s there.

Weird Router Login Issue

hp — Tue, 11 May 2010 06:07:06 +0000

So I just upgraded my router (DGL-4500) to the latest firmware today (1.22), and I started experiencing this weird bug where I couldn’t log into the router page. Every time I typed in my password, the router would deny me access. According to the D-Link forum, pressing the Login button rather than pressing the Enter key works. For some weird reason, that fixed it.