Welcome to the most active Linux Forum on the web.
Go Back > Forums > Linux Forums > Linux - Networking
User Name
Linux - Networking This forum is for any issue related to networks or networking.
Routing, network cards, OSI, etc. Anything is fair game.


  Search this Thread
Old 11-11-2015, 09:00 AM   #1
Registered: Oct 2005
Location: SW Ontario Canada
Distribution: Debian
Posts: 138

Rep: Reputation: Disabled
Computer connected to LAN causes DSL modem to stop Rx Tx?

I have a LAN set up with 6 or 7 PC's connected some wired and some wireless. Also there are a number of Arduinos connected with ethernet shields which do data collection.

I have been having problems with my DSL connection and have isolated it to one PC, a tower with an Asus board and AMD phenom processor running Debian Wheezy. This machine has been operating for a least 5 years. It is always on, it is the database server for the data collected by the Arduinos.

As soon as I plug its RJ45 connector to the LAN (to the router) my DSL modem quits working. The ADSL stays on but all Rx and Tx lights quit and non of the other computers can access the internet. The LAN continues to operate normally, ping times are normal, etc.

When I unplug the RJ45 of the offending computer my DSL connection goes back to normal.

This seems to have happened suddenly and nothing else has changed on the LAN. I'm pretty sure that there are no conflicting MAC or IP addresses. The main router is a Cisco / Linksys E4200. The other switches are mostly D-Links and there is one pair of Engenius WAPs set up as a bridge.

Any ideas about what could be wrong?

Old 11-11-2015, 10:05 AM   #2
Registered: Aug 2003
Distribution: Mandrake 9.0; FC4; FC8; SUSE 10.3; SUSE 12.1; SUSE 13.2
Posts: 638
Blog Entries: 1

Rep: Reputation: 52
For the PC that is causing the problem, what happens if you add a new network card to it and use that new network card to connect that PC to your LAN?
Old 11-11-2015, 11:01 AM   #3
LQ Sage
Registered: Nov 2004
Location: Saint Amant, Acadiana
Distribution: Gentoo ~amd64
Posts: 7,661

Rep: Reputation: Disabled
Have you tried to use another port on switch?
Old 11-12-2015, 05:36 PM   #4
Registered: Oct 2005
Location: SW Ontario Canada
Distribution: Debian
Posts: 138

Original Poster
Rep: Reputation: Disabled
Well, this is embarassing, my problem was an ip address conflict. I had three routers set up as WAP's that all had the same ip address. Two of them have been that way for over ten, yes 10, years. I thought (based on manufacturers documentation) that once you set a router to WAP only IP settings don't matter any more, but NO!

It is even made worse because I had a "somewhat" similar problem when I set two Arduinos up with the same IP.

Why it blew up all of a sudden, I don't know. Knock on wood.

P.S.: Emerson, thanks for the Master Foo link.

Last edited by jogl_z_8; 11-12-2015 at 05:58 PM.


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
how to find the ip address of a computer that is connected to LAN gajaykrishnan Linux - Networking 7 12-03-2010 05:38 AM
Linux box security when net connected via router and DSL modem ? uncle-c Linux - Security 4 08-19-2008 08:54 PM
Computer hangs when modem is connected fenritz Linux - Hardware 3 04-17-2007 08:14 AM
Computer accessing lan but not dsl on it suman_rath Linux - Networking 3 06-28-2005 06:36 PM > Forums > Linux Forums > Linux - Networking

All times are GMT -5. The time now is 12:03 PM.

Main Menu
Write for LQ is looking for people interested in writing Editorials, Articles, Reviews, and more. If you'd like to contribute content, let us know.
Main Menu
RSS1  Latest Threads
RSS1  LQ News
Twitter: @linuxquestions
Open Source Consulting | Domain Registration