We have a Startech KVM over IP model SV841HDI and it was stuck pointing a port where the machine has been removed. We ended up having to physically plug something into that port in order to switch ports again, meaning that if someone in support accidentally switches to an empty port, we need to have a documented solution for making it useable again.
The unit is old, no longer under warranty, firmware updates for it are no longer available (interestingly it runs a powerPC version of busybox). Since it does work well except for this one catch, we would like to avoid replacing it.
Reading the manual, you have a several recommended methods. I tried them. Hit the left CTRL key a few times (as well as all the other popular KVM keys I could think of). The VNC GUI offers lots of buttons - none of them switch away from a dead port.
The question is: how do I switch away from a dead port on this particular KVM remotely?