2 cameras do not work via usb hub, who is to blame?

Question

Raspberry Pi

There is a raspberry pi b . Also 1 usb hub for 4 ports, 2 web cameras, 1 3g modem.
When connecting two cameras to a raspberry directly (without a hub), I can start streaming to each camera without any problems.
But there is no room for a modem.
Bought a usb hub.
Cameras connected via the hub do not want to start. However, they are in the system as /dev/video0 , /dev/video1.
Unfortunately, I am writing this message without the presence of this assembly nearby. Because of this, I can not post the logs right now.
I'll post any logs tonight.
Could the problem be in the hub itself?
Thank you attention

Answer 1

It is very possible that there is not enough power, especially if the hub does not have a separate external power supply.