mcbsys

Well, the same cable works fine with three Cisco switches. Maybe it's the physical port.

I gave up and did a factory reset. The console still doesn't work.

@Zyxel_Cooldia, thanks for your reply.In Device Manager on my laptop, the USB cable usually shows up as COM5. I adjusted PuTTY and TeraTerm to COM5, but still got a black screen. On the server, the direct COM port cable shows up as COM1 in Device Manager. PuTTY was set to COM1, but still I got the black screen.