Discussion How many hard drive docks can my machine have connected at once?

[DataDestroyer2021]

Can anyone tell me how many external hard drive docks a pc can have connected at once and for them all to run?
I have a set up that current has 25 docks using 2 USB extenders, all components are individually powered but the system is showing only 8 hard drives even though I have more conected.
Any hints tips or setup advice welcome!!

 

[RealBeast]

What shows up in disk management, and are any of the unusable drives shown in DM as offline at the bottom of the list of drives? Do they all have distinct drive letters?

[One other thought: If you are using USB 3.0, I suspect that you may be hitting USB EndPoint limits, as each device uses a number of them and USB controllers have a limitation on the number of end points that they can handle (often 96)]