Re: Resetting a RJ45 port in a router

On Mon, 8/24/2026 12:36 PM, Mr. Chang Man-wai wrote:
> 
> Could I reset a RJ45 port in a router or
> by sorting of the 8 pins in the
> RJ45 connector?
> 
> I got a strange router that if it's
> powered on with the WAN port
> connected, there would be no
> internet.I dunno whether it's my
> router's problem or the device
> (ISP?) upstream from the WAN
> port.
> 
> So maybe I could just reset the WAN
> port by sorting 2 pins using a
> little switch instead of re-plugging
> the RJ45 cable at the WAN port. ;)
> 

Maybe you could re-flash the firmware on it ?

*******

Ethernet RJ45 ports are transformer-isolated.
There is no DC path between one side and the
other of the transformer. Shorting the pins
would definitely have an effect... on the
pad drivers on the other side of the transformer.
But that does *nothing* to change the logical
state of anything.

This is an "Ethernet splitter selector switch".

   https://www.amazon.ca/Gigabit-Network-Splitter-Selector-Support/dp/B0CL8XVQ77

When you use the plastic knob on the splitter,
it would be like unplugging the wire, only switch-operated.
It's an eight pole double-throw switch. The second
port on the two-port side, is not used and the X means
"not connected to anything".

   --------->\
              \__________Out----> router
         X-->

The only question about junk like this, is the
quality of the switch. Is it a good switch, or
would it wear out rapidly ? We don't know.
The top of the box is labeled "A" and "B", and
the switch moves side to side.

To use the splitter selector switch, you must
purchase at least one extra cable.

   Paul