The forum post below provides useful context on how the LEDs work on UbiSwitch.
The LED lines are multiplexed, so one line does not correspond directly to one LED signal. The schematic below shows how they are connected.
The lines named on the connector are shown below.
EE_CLK_C0_LED_P1_LED0_FLOW = C0_LED (C0 printed on the board)
EE_DOUT_C1_LED_P6_LED0 = C1_LED
C2_LED_P7_LED0 = C2_LED
C3_LED_P8_LED0 = C3_LED
R0_LED_P1_LED0 = R0_LED
R1_LED_P2_LED0 = R1_LED
By connecting the Column lines (C0, C1, C2, C3) and Row lines (R0, R1) in specific ways, you can access the LED lines as needed.
The table below shows how the rows and columns correspond to different LED signals. Each port has two LED signals associated with it, one for activity, and one for link.
||Port 1, LED0
||Port 1, LED 1
||Port 2, LED 0
||Port 2, LED 1
||Port 3, LED0
||Port 3, LED 1
||Port 4, LED 0
||Port 4, LED 1
Off = No Link
On = 1000M link
Blink = 1000BASE-T activity
Off = No Link
On = 10/100M link
Blink = 10/100 activity
These LED signals are designed for use with dual colour LEDs. This allows a single LED package to display both link speed information (with colour) and link activity information (off/on/blink).
To clarify how you connect an LED… For Port 1, 1000M link/activity LED, you would connect an LED between C0_LED (anode) and R0_LED (cathode).
If you are using a single colour LED, you would only be able to use either the 10/100M or the 1000M link/activity combination, which is not ideal.
You mention that your LEDs do not blink, and are always on. Please share your schematic for how you have connected your LEDs so we can check.
Regarding LED brightness, R4 and R5 (150 Ohm resistors) limit the current flowing in both the onboard LEDs, and your external LEDs. For your external LEDs, you can either add them directly on the LED header (in which case, the R4 and R5 will limit the current flowing through them), or you can add additional resistors in series with the external LEDs to reduce the brightness.
Note that the LED anodes (C0 to C3) are 3.3V level signals.
You should avoid modifying R4 and R5. Please note that modifying the board will void the warranty.