Hi,
Sorry for stupid question…
Usb port work like a hub?
Thank you
what do you mean “work like a hub”?
Which product are you referring to?
opkg update ; opkg install usbutils ; lsusb
wait maybe asking if you could use male to male usb cable for powering router? no, not, never.
sorry for badly question.
Is possibile to connect an usb hub on usb port (ar750, b1300)?
Yes of course. Just connect and it works. That is how USB hub works. Plug and play.
Just be careful how many USB device you put in and how much power they draw 
It is recommended you use a powered usb hub
thank you at all