Problem 8: Press the button on the KVM switch and fail to switch.

Solution: First, pay attention to the switch’s indicator light and see if the light changes to the device you are switching to when the button is pressed; If the switch indicator light does not change, press the switch button a little harder to ensure that the button is pressed in place and see if it works. If the KVM switch supports infrared remote control or hotkey functionality, use these to test and confirm whether the switching of the KVM switch is faulty.

Problem 9: The video works flawlessly, but there is no audio output from the 3.5mm jack.

Solution: Firstly, check if the USB host cable is well connected and whether your USB devices are working correctly. The 3.5mm audio data is transmitted through USB. Secondly, check the 3.5mm audio plug of your headphones. There is a 3-pin 3.5mm plug to transmit speaker and microphone separately; and a 4-pin 3.5mm plug to transmit both audio and microphone in one port. Please refer to your device’s manual for the specific 3.5mm port specifications and use the right device for connection. If you’re using the right headphones for the port, check in your PC/laptop’s settings if the USB headphones are set as the audio output device.

Problem 10: With the KVM switch connected, USB devices intermittently disconnect.

Solution: Check the USB cable connection between the KVM switch and your computers. Try replacing it with a shorter, higher-quality USB cable to see if the problem is resolved. You can also connect the USB device directly to the PC host without going through the KVM switch to see if it works properly. If it’s working fine, try restarting the KVM switch to see if the issue can be resolved.

Problem 11: Unable to wake up the computer using the keyboard/mouse.

Solution: Try connecting the keyboard/mouse directly to the PC without using the KVM switch to ensure they can wake up your computer from sleep or hibernation mode. When using the mouse to wake up the computer, you may need to click the mouse rather than just move it.

Problem 12: The infrared remote of the KVM fails to switch.

Solution: First, check if the indicator on the remote control lights up when you press any of the buttons. If it doesn’t light up, it’s possible that the battery is running out. Replace it with a new one.

If the indicator does light up, bring the remote control right close to the KVM switch’s infrared receiver to see if the switching works. If the switching function works properly when it’s close to the IR receiver, it’s possible that the remote control was previously out of range.

Note: The infrared signal receiving range is typically around 7–8 meters and it works depending on the angle of the remote control.

Problem 13: Hotkey switching is not working.

Solution: First, make sure the keyboard is connected to a USB 1.1 port. The hotkey switching feature only works with a USB 1.1 port. If it’s well connected to a USB 1.1 port, try using a different keyboard to test if it’s a compatibility issue (you can provide specs information, such as the keyboard brand and model to check with the manufacturer). For some KVM switches, the hotkey switching feature may be locked in some way. Check the user manual and make sure that you have enabled it.

Problem 14: The USB-C device only shows duplicate instead of extended screens.

Solution: Confirm whether the USB-C In port supports DP Alt mode or MST mode. If you are using a MacBook as the input source, note that the latest MacBooks’ ARM processors only support DP SST mode, which means that the two external monitors will display the same content.

Problem 15: Unstable keyboard and mouse control.

Solution: USB-IF has confirmed that USB 3.0 can interfere with 2.4GHz wireless mouse and keyboard receivers. This is because the actual transmission rate of USB 3.0 devices such as portable hard drives is typically around 2.4GHz, which is close to the transmission rate of 2.4GHz wireless mouse and keyboard receivers. This can lead to interference when USB 3.0 devices are connected to USB ports that are near the keyboard and mouse receiver. Therefore, if your wireless keyboard and mouse are working with an unstable connection, check if USB 3.0 devices are connected near the wireless adapter. To minimize the interference, connect your USB 3.0 device to a port farther away from the wireless adapter.

Source: https://www.avaccess.com/blogs/guides/common-problems-with-kvm-switch-2/