Posted inInformation Technology

How to Find Your Range Extender’s IP Address

seasoned_geek by seasoned_geek

“How to find your range extender’s IP address?” is a sad question to have to ask. It’s a result of a network change. Not an automated, flawless change, but a series of forced manual changes and you not realizing until it is too late that you cannot access the admin page.

The backstory

Some of you are aware that I live rural when I’m not traveling for IT work. Went from paying $300/month for dial-up Internet (all of the access numbers were long distance) to various USB dongles from Verizon, Sprint, and AT&T plugged into a Cradlepoint router. Even had DirectPC and HughesNet.

I’ve had everything but actual cable trenched to the house. Honestly, I looked into that years ago. They wanted $8,000/mile and they needed to come about ten miles. That was north of twenty years ago. I don’t think it has gotten any closer because they always want to charge us to trench the cable.

For the past few years I’ve had Line-of-sight Internet and I keep a pre-pay Verizon 4G Jetpack around in case there is some huge outage while I’m working remotely. I must have pitched the Cradlepoint because I couldn’t find it to take pictures. It had a nice fail-over feature where you could set up a primary Internet port and tell it to use a cellular dongle when that Internet went down.

The experience has lead to some posts over the years. 2011 Adding WiFi to Your Whole Farm. Whole Farm Wifi 2015. 2017 Beware Range Extender Max Number of Users. Now it has lead to this one.

The recent event

Some tower upgrades had to happen a while back. There were six of us lucky customers whose radios had to have a firmware update that physically refused to apply from the tower. He was out in his van a long time trying to figure out what was wrong. Gave him access to my router and went about my day. Several hours later he left and I could check email.

After heading back out to my office I found I could not print to my color laser printer. This always had a fixed IP address reserved in the router. The reason for the fixed address is that I had a DS10 Alpha for many years.

DS10 Alpha and external SCSI enclosure

It was just easier to have an IP address when I set up a PostScript print queue. The Alpha went to recycling several years ago and I never bothered changing the printer. You don’t fix what isn’t broken.

After a bit of poking around I found the IP address of my router was different in the third group. Odd I thought. That printer was the only device not setup for DHCP so I manually went through the menus on the printer. When you can’t see it on your network, that is your second best option.

Lexmark CS310dn

After changing both interfaces to DHCP and rebooting the printer I could see it and print to it. This printer is good enough for my own personal printing, but I wouldn’t send anything out printed on it now. I’m just waiting for the last of several hundred dollars in toner to go through it before replacing it.

In hindsight, I really should have dug deeper

Ever since then I’ve had these periods of dramatic stutter-sputter Internet access. I kept reporting the issue and Amber couldn’t see anything on her end. (Yes, my line of sight provider is a small company and we know names.)

Yesterday this computer I’m typing on now just seemed to be dying when it came to network access. Not just Internet access. My NAS was difficult to reach. Print jobs went off into the mist for 10+- minutes before finding the printer. I noticed I was connected to the 2Ghz band because it showed the strongest signal. Forced the wifi to use 5Ghz and life seemed to get good.

This morning I had to dig into the problem. That was when I found Mike switched my router to be a bridge. It got me on the Internet, but a heads up would have been nice. The only real downside is that now the router doesn’t have a nice little list of connected devices because it isn’t providing DHCP in bridge mode.

My suspicion was that the regizzing of the router cause the range extender to use some default of 2Ghz connection, forcing all of my network traffic into that narrow little horse and buggy channel.

To confirm this I needed to access the admin page. None of the URLs in the documentation would bring the page up. As a last desperate gasp the documentation says to “use the IP address.” That sent me into the house where the router is and showed me it is now a bridge and as a bridge doesn’t have that nice little list.

There are command line tools, right?

Yeah. If you do networking you probably have everything installed. Those of us who don’t want to get that close to the metal anymore tend to only know a few. On Windows you are kind of screwed.

arp -a

You open a terminal with “Run as Administrator” and you type 

arp -a

You can see the output (with my IP addresses smudged) in the above image. I tried every IP address in the browser and none of them opened up the range extender admin page. Took my laptop out to the office in case I had to be on the other side of the range extender to see it and same result.

Try Manjaro

The table I was working at had a machine on it running Manjaro. Linux distros just have to keep pissing people off. None of the old standby network tools are there. Not even ifconfig. If you want to know your machine’s IP address you have to type

ip address

A bit of fumbling around had me doing the following.

sudo pacman -Sy arp-scan
arp-scan output

The command I used was:

sudo arp-scan --interface=wlp6s0 --localnet

You need the output of “ip address” to know what interface value to use. What is really really nice is the fact it gives you the manufacturer names. As you could see there was only one Netgear device.

Yes, the reset had dropped everything back to channel 1, the lowest, weakest signal. I changed back to the highest channel/frequency and life is good!

Roland Hughes started his IT career in the early 1980s. He quickly became a consultant and president of Logikal Solutions, a software consulting firm specializing in OpenVMS application and C++/Qt touchscreen/embedded Linux development. Early in his career he became involved in what is now called cross platform development. Given the dearth of useful books on the subject he ventured into the world of professional author in 1995 writing the first of the "Zinc It!" book series for John Gordon Burke Publisher, Inc.

A decade later he released a massive (nearly 800 pages) tome "The Minimum You Need to Know to Be an OpenVMS Application Developer" which tried to encapsulate the essential skills gained over what was nearly a 20 year career at that point. From there "The Minimum You Need to Know" book series was born.

Three years later he wrote his first novel "Infinite Exposure" which got much notice from people involved in the banking and financial security worlds. Some of the attacks predicted in that book have since come to pass. While it was not originally intended to be a trilogy, it became the first book of "The Earth That Was" trilogy:
Infinite Exposure
Lesedi - The Greatest Lie Ever Told
John Smith - Last Known Survivor of the Microsoft Wars

When he is not consulting Roland Hughes posts about technology and sometimes politics on his blog. He also has regularly scheduled Sunday posts appearing on the Interesting Authors blog.