A common call while troubleshooting KVMs is the fact that the keyboard and mouse are not working with their switch, and they can't figure out why. More often than not there are adapters the customers are trying to use and they are converting PS/2 to USB because their computer no longer has USB ports. While it seems simple enough, doing this can throw off the KVM switch and the PC. When your computer boots, if it does not see a keyboard and mouse attached it will notify you of this. A KVM switch achieves the ability to use 1 keyboard, monitor, and mouse by emulating these signals to the computer, thus allowing it to boot without any hitches. When these adapters are thrown in they are not providing that emulation, and it will appear no keyboard or mouse is attached. Other common problems in situations with no keyboard or mouse are related to PS/2 connectivity and needing a reboot, or possibly just disconnected or bad cables or even KVM hardware. As a conclusion to the thought about the emulation, there are converters that have the electronics built into them to accomplish this. If you're still having keyboard and mice trouble, check that you're not using wireless equipment unless the switch supports it. Make sure you have the correct drivers installed on all PCs. Of course there are other problems that can arise but its all hypothetical at this point.
Also a shoutout to Garrett and his site dedicated to teach people how to make MMORPG games. He put alot of time into it and it looks nice and he definitely has experience with it. Guide to Making an MMORPG