Trouble with wifi usb rt3070

I'm trying to make work that usb wifi so after the installation of kmod-rt2800-usb and dependencies the dongle is recognised and start working but at reboot it doesn't work any more.
Detaching the usb and reconnecting it reappears but need to be connected and reconnected at each boot.
If rebooted by ssh or luci the router does not boot at all, must be powered off to make it boot again.
It happened also sometimes that if detached when router is powered and reconnected is newly found as a new radio device so in /etc/config/wireless I have two radio for the same usb one with path ehci.... an the other ohci.....

It's driving me crazy...