You keep asking about the same issue concerning your gaming problem. #1 your internet connection is slow at best and you probably never get the full upload speed you have 4 devices and have a half a meg for upload MAX, that is your problem! Even if there are only two devices running that is .25 of a M... Your sister will experience buffering problems nd you will get the dreaded lag problems. You need more bandwidth, buy it and be done with it!
Try this, have your sister turn off her computer and see what happens. A half a M is not great for gamin...BTW is your computer clean?
Please watch this video: http://www.youtube.com/watch?v=juA0mxhottM
What about that CMTOOL upload speed increase? Will that improve when tablet connected wirelessly and my laptop connected wired?
Yes buy more bandwidth!
The fact that it doesn't occur when she is on proves that is she is using up the bandwidth that you need.
When she watches a movie she will get a large burst of data, when that happens your ping times to your game server will increase and you will see your game lag.....This is a text book 101 problem.
If you could enable some sot of QoS then it still would not help. I have 10/1 at my house now but before we had 5/.5 my kids would complain when I was watching Netflix. It still does it a bit.
You will need more bandwidth, your existing router to be bridged , then buy your own router and set up QoS for your gaming computer or gaming device to prioritize traffic for it.