sergeyvl12, you can pause nickel using this linux command: kill -STOP <PS NUMBER OF NICKEL>
Then start your custom QT app, after that:
resume it like this: kill -CONT <PS NUMBER OF NICKEL>
It works very good, and the wifi stays connected. The only thing is, that nickel thinks the time has changed and ask you for the right time. Lot more simpler then restarting nickel!