Only Sys light is on the fiber optic switch
99% of the time, the problem is fiber polarity — specifically, Transmit (Tx) talking to Transmit and Receive (Rx) talking to Receive instead of Tx ↔ Rx. Good news: it's incredibly easy to understand and fix once you know the "two-lane highway" rule. I suspect it might be a single-mode SFP, as I wouldn't see the 9-port switch light up otherwise. Status Light: An LED indicating the system's operating status, usually a dual-color (red/green) light. It flashes green during the initialization phase, remains solid green after successful initialization, and turns red when a system fault occurs.
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