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I have my laptop plugged in with an ethernet cable at work. It gives me internet. Two weeks ago it started becoming intermittent. At apparently random intervals I cannot load any more web pages. Firefox will try for a long time to load any pages, and in the end it says "server not found." If I wait about five minutes, it will start working again.

It is not just firefox: Dropbox loses it's connection too.

The network manager gives me no errors or complaints. I have disabled wireless, thinking that my personal hotspot might be interfering with it.

My colleague has a different ethernet cable plugged into her computer, and she has no such problems with her internet connection. I used her cable with my laptop, but the problem remained.

I have dual boot. I tested the connection with Windows 7, and with substantial browsing the problem didn't arise. It seems likely that there's something fishy going on with my Ubuntu installation. I may test with Windows again, just to make sure.

I updated Ubuntu today.

What can I do to find the cause of this problem?

Thank you so much.

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up vote 0 down vote accepted

The network I am on is administrated poorly. I used to get a lot of IP address conflicts. Knowing this to be the case, I tried spoofing my MAC address. I used macchanger.

I have now been using the internet for an hour without any timeouts or slowness. It looks like this fixed it.

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