I have searched, unsuccessfully, for any documentation on the Ethernet LEDs and asked on the Forum, but got no replies.

`dtparam -h eth_led0 eth_led1` produces the following, but it is unclear what most of these mean.

```
eth_led0                Set mode of LED0 - amber on Pi3B+ (default "1"),
                        green on Pi4 (default "0").
                        The legal values are:
                        Pi3B+
                        0=link/activity          1=link1000/activity
                        2=link100/activity       3=link10/activity
                        4=link100/1000/activity  5=link10/1000/activity
                        6=link10/100/activity    14=off    15=on
                        Pi4
                        0=Speed/Activity         1=Speed
                        2=Flash activity         3=FDX
                        4=Off                    5=On
                        6=Alt                    7=Speed/Flash
                        8=Link                   9=Activity
eth_led1                Set mode of LED1 - green on Pi3B+ (default "6"),
                        amber on Pi4 (default "8"). See eth_led0 for
                        legal values.
```

On a Gigabit router:-
```

The **Pi3B+** amber LED blinks.
The Green LED is off.

The **Pi4** amber LED is on.
The Green LED blinks.

The Pi3B amber LED  is on.
The Green LED blinks.
Speed: 100Mb/s
```

There appears to be no consistency.

Out of curiosity I ran the command on my PiB+ running Stretch

```
eth_led0                Set mode of LED0 (usually orange) (default
                        "1"). The legal values are:
                        0=link/activity          1=link1000/activity
                        2=link100/activity       3=link10/activity
                        4=link100/1000/activity  5=link10/1000/activity
                        6=link10/100/activity    14=off    15=on
eth_led1                Set mode of LED1 (usually green) (default
                        "6"). See eth_led0 for legal values.

```