Is my RT-AC86U dying?

Jerry Loh

Occasional Visitor
So I bought a UART serial cable and I watch the console and it doesn't boot up when serial is connected. Quite a newbie in this, hope anyone can guide me. Thanksss

@vaboro @Tech9 @ColinTaylor

Too long contents have to move to pastebin.

CFE> help
Available commands:

otpcfg              Reading/fusing potp/sotp bits
x                   Change extra partitions size
find                Find string in NAND
comp                Compare NAND blocks
fb                  Find NAND bad blocks
dn                  Dump NAND contents along with spare area
phy                 Set memory or registers.
meminfo             Display CFE System Memory
kernp               Updates extra bootloader parameter for kernel. To end input enter // consecutively at any time then press <enter>
sm                  Set memory or registers.
db                  Dump bytes.
dh                  Dump half-words.
dw                  Dump words.
w                   Write the whole image start from beginning of the flash
e                   Erase NAND flash
wp                  Write pmc (previously loaded through JTAG to flash block 0.
ws                  Write whole image (priviously loaded by kermit or JTAG) to flash .
ldt                 load device tree blob from tftp server.
go                  goto and execute from specefic address.
loadb               load binary via network or kermit protocol.
r                   Run program from flash image or from host depending on [f/h/c] flags
p                   Print boot line and board parameter info
c                   Change booline parameters
i                   Erase persistent storage data
avs                 Change AVS config
ddr                 Change board DDR config
a                   Change board AFE ID
b                   Change board parameters
reset               Reset the board
pmdio               Pseudo MDIO access for external switches.
spi                 Legacy SPI access of external switch.
pmc                 pmc cmd
closeavs            pmc close avs cmd
cpufreq             set CPU frequency
force               override chipid check for images.
help                Obtain help for CFE commands

For more information about a command, enter 'help command-name'
*** command status = 0
CFE> fb
>>>>>>>> FIND BAD BLOCKS from block 0 to block 0x7ff <<<<<<<<
Block 0x2f9 is marked bad
*** command status = 0

Can't get Asus Firmware Restoration Utility to work although it's in rescue mode already. also shows nothing (don't have CFEminiServer).
Let me know if y'all need more stuff/troubleshooting steps. Once again thank you and I am appreciate for any help!


Part of the Furniture

I never used any software fixes on AC86U. I had one boot looping and used it for donor parts. I don't think AC86U is worth saving.

Jerry Loh

Occasional Visitor

Hi, I just replaced my old power adapter which is causing some of the problems when changed to higher power region. It was only outputting 8-9V constant compared to new is 19V constant.
And also I think need to replace the NAND flash (MX30LF2G18AC-TI), maybe it will become good again. Is that correct?
Last edited:


Part of the Furniture
It was only outputting 8-9V constant compared to new is 19V constant.

Change the power supply and if the router is booting, try re-flashing stock Asuswrt firmware with Firmware Restoration Tool or via Mini CFE Web.

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