Lag problem / high netgraph

[Chef-Killer]

I have some lag problems for a few month, if there are more then 3 or 4 player on the server. I didn't change anything and my internet connection looks ok (T3RR0R can play normal with the same internet, i just have wlan). It came from one day of another day.

Have anyone an idea, what could it be and what could i do against it?

Here is a laggy demo:
http://otbclan.ot.funpic.de/otb/lag.dm2

Here is a screenshot of the netgraph:

[jitspoe]

The black lines are packet loss.  Is this happening on a specific server or everywhere?  Try disabling any virus scanners, firewalls, or packet schedulers.

[Chef-Killer]

I tried already, but it doesn't help.

It is on all servers, this one was the OTB-Speed, there it is extreme, i have almost a standing picture.