Lag and packetloss solved

Well, this was a wild one and maybe it will help someone else.

My network is done through the phoneline. I had my desk phone plugged into the USB phoneline networking device I use. When I unplugged the phone, all of a sudden SL works, and works great.

Since I know I'm a rarity with my type of network, it might not help anyone. But you may want to check if a phone is plugged into your computer or other device that goes into your computer.

I'd be curious to know if it helps in any way.

It almost sounds like you have DSL but I get lost on the "my desk phone plugged into the USB phoneline networking device I use" part..

If it is DSL, you need to put a filter on *everything* that plugs into the phone system except the DSL modem itself..