I am able to enter the following:
interface ethernet 1/5 speed 40000 force
quadrupling the default speed of 10000. Attempting to substitute 20000 results in an error that it is not supported. As soon as the speed increase goes into effect, I lose any active connection or the ability to find the connection to activate. I am guessing that this speed exceeds the capability of a UART or whatever device(s) support the serial DB connection. Is there another likely explanation?