How to enter UBOOT in XE3000?

I am a loyal user of GL.iNet. I have previously purchased MIFI, XE300, and AX1800 for myself or my friends. Now, I have received my newly purchased XE3000. The model on the back of the router is XE3000NR.
Now, my problem is that I don’t know how to access the UBOOT interface of this XE3000 router. Since this model is not in the official documentation, I tried the following operations:
disconnect the power and turn off the device, hold down the reset button, plug in the power and the device will automatically turn on.
At this time, the “Internet” LED light is flashing. When it flashes 5 times, I released the reset button, and then the 2.4GHZ LED light of WIFI will light up.
Now my problem is that this WIFI light will only light up for a few seconds and then go out.
I only use a network cable to connect my computer and the XE3000 router, and set the IP on my computer to At this time, I cannot access the uboot interface at through Chrome.
I suspect the problem is that the WIFI LED light will automatically go out.
Can you tell me how to solve this problem? Thank you all.

I have reproduced this situation if I turn on device without network cable connected. So please connect network cable before power the device.

I don’t think it’s that simple. I can’t connect my laptop using an Ethernet cable, but I can connect it using a SUB Ethernet adapter. I don’t know why this is the case.

So you are telling that the internal Ethernet does not work but an USB one does?

Only the LAN port works for uboot, not use 2.5G WAN.