Issues with ZBT Z8103-AX

I have two general questions about upgrading this router to the latest OpenWRT snapshot build.
I'd like to share more of my experience with upgrading its firmware. I've had two units, one ordered from AliExpress in Feb-March last year, and another purchased in May-June last year.

Successful Upgrade of Second Router

My second router is working fine after upgrading to OpenWRT snapshot using the openwrt-mediatek-filogic-zbtlink_zbt-z8103ax-squashfs-factory.bin file. Here's how I did it:

• Connected a UART cable to access the terminal
• Discovered the "U-boot web fail safe" option, which allowed me to upload the firmware via
• Successfully upgraded the router, and all is well

However, I'm still unsure if there's a way to activate the U-boot web page without a UART cable. If anyone has a solution, please share!

Challenges with First Router

When I tried to replicate the process with my first router today, I encountered issues:

• Couldn't access the "U-boot web console" in the boot menu, despite multiple attempts
• TFTP upgrade with the same firmware file failed

It seems that the U-boot configurations on both routers are different. Can anyone help me figure out how to access the "U-boot web" page on my older router?

See a linked discussion here: ZBT Z8103AX-D: upgrading from 21.02 to 23.05