Network setup

[EMPiRE]

First off, I do not have a clear answer as this problem is not a common one

If your downloads slow down when your laptop connects then this is not normal:

1. It could be that your router is malfunctioning (or due to a mis-config)
2. The laptop, for some reason starts uploading (or downloading) something at full speed, thus saturating your upload speed, which will cause downloads to slow down (a mailvirus/worm could be the cause), you can check this with a bandwidth monitor: http://sourceforge.net/projects/freemeter/

I am only aware of one (low-budget) brand router which is able to cap WLAN upload/download speeds, that are the ones from Draytek

What you can do is upgrade the firmware of your router to the latest one, write down your config settings before the update as it will kill your current config.