I've run into two issues with Lantronix based KVMs on various servers and here's how I solved them (with that said I like these units as they are Java based and OS independent and work very well, unike some other models like Startech).
1.) If you are connected by USB only and you're sure USB support from the BIOS is enabled, you just need to click the following in Lantronix
Interfaces -> Keyboard/Mouse
Check "Force USB Full Speed Mode", this fixed the issu........