Ive got bitHopper running on my main machine with 2 GPUS, and 10 more miners from other machines that connect to it. Including browsing the internet I have used 61.7MB down and 25.6MB up today. Do you have some other software doing auto updates or something in the background?
ok, I think, the first important step will be the miner on the second PC connect to this PC's bithopper...
(because now it is running here 2 times)
how can I do this (if the ip changes every reboot)?
If your talking about your LAN, you could always set a static ip or setup a dhcp reservation. I just use hostnames, works good so far.