I have a Lindy High Speed HDMI KVM switch for two PCs that switches HDMI and USB. The KVM switch provides two physical USB ports. But I need three (keyboard, mouse and WebCam). So I thought I'd plug in a USB hub to get more USB ports. The KVM's page even says:
Additional USB accessories can be attached using a USB Hub (not included)
But that doesn't work. When I've plugged in the HUB and switch PCs on the KVM, it works momentarily and then switches back to the other/original PC. Even if there is only one device connected to the USB hub. I've tried multiple USB hubs that otherwise work. Both ones with external power supplies ("self-powered"/"active") and ones without a power supply ("passive"), so I don't think it is a problem with the USB hub. The answers to this question: Is it possible to use a usb hub with a kvm switch? seem to indicate that it should work, but it actually doesn't.
What could be the reasons why USB devices work when plugged in directly to the KVM switch, but that the KVM switches back to the original device after a few seconds when the USB hub is used - even if only one USB device is connected in the hub and even if the hub is "self-powered"/"active".
(Oh, and I need 4K HDMI or DisplayPort graphics support, but I'm pretty sure that is irrelevant to this.)
