DIgiPortserver TS 16 problems

I can’t get a stable signal to and from my devices while using the 10pin RJ45 connectors. Can someone please explain to me the differences between signal ground and chassis ground?

Signal ground is the reference point for the RS232 signals, and corresponds to pin 7 on the 10-wire RJ-45, also pin 7 of a RS-232 DB-25 connector. Chassis ground is same as frame ground or shield, and corresponds to pin 4 of the RJ-45 10-wire connector, or pin 1 and/or shell of a RS-232 DB-25 connector or braid on a shielded cable.

The two are seperate grounds, and must not be connected together due to ground faults, etc.