Maximum number of usb devices?

Question

USB

Good afternoon!
Interested in the question of the allowable number of connected usb devices. Maybe someone came across.
Now supermicro has two active usb hubs and 10 usb modems. Ubuntu serv 18.04
100% is enough for relics
10 devices defines perfectly, everything works, traffic runs.
How I try to put more - does not determine.
As I understand it, the limitation of the mother herself is that more than 10 devices cannot process streams.
No one found motherboards with a large number of usb in the open spaces of the network? Ideally, you need to support 20 devices at the same time.
I thought to install additional pci expansion cards, but how the drivers behave is not clear.

Answer 1

Theoretically, Microsoft declares up to 256 devices. In my case, the maximum was 10 connections via USB hub and everything flew without obvious slowdowns.