RT-AX88U Pro Unresponsive

[el_vandragon]

A few months ago I ran into an issue where with my AX88U Pro where WAN would randomly disconnect after a while so I did a factory reset and I still ran into the issue so I decided to set it aside and use other hardware I have and come revisit this when I had time. (As a note at some point I had Asuswrt-Merlin firmware on it but I can't remember if I restored to stock or not before I set it aside)

I just started trying to set it up again and I can't get it to do anything at all. When I turn it on only the power LED goes on and no matter how long I let it sit I can't get it to pick up a my WAN connection or even let me connect to it via ethernet to try and configure/debug it that way.

1) First I tried leaving router unplugged for a while, and unplugging AC adapter from wall for a while, and switching to a different outlet to see if that may be related but that didn't seem to have any effect.

2) I tried to see if I could do a firmware restore following the steps from the manual (unplug, hold reset button, replug, turn power on, wait for power led to flash, release reset button, use windows fw tool), however the power LED would not flash at all no matter how long I held the reset button.
- (times myself, held reset for 10s with power unplugged, then 30s after plugging in (power was already on)).

3) Then I tried a hard reset via ASUS method 2 following the steps from the support website here (turn off, hold WPS button, turn on, wait for power LED to turn off, release WPS button, power cycle router), however again, the power LED would not turn off and it did not seem to perform a reset of any kind no matter how long I held the WPS button
- (timed myself, held WPS for 10s with power off, then 30s after powering on).

Any ideas on what I could try next or what might be the issue with it? Thanks in advance!

 

[PunchCardBoss]

Any ideas on what I could try next or what might be the issue with it?

Just a guess. Are you using the AX88U-PRO power brick. Or are you using the brick from your older router?

 

[el_vandragon]

Just a guess. Are you using the AX88U-PRO power brick. Or are you using the brick from your older router?

I am using the one that came with the AX88U Pro, it is an AC Bel 19.5V / 2.31A (45W) power supply. It has a removable 3-prong cable on the AC side (I tried replacing this) and then a fixed cable with a barrel jack coming out of the power supply.

I just used a multimeter to measure the output voltage and got 19.98/19.99 V, not sure if that is okay since there is no load or if it is an issue that it is ~0.5V higher than it is supposed to be. Maybe there is an issue with the power supply after all.

 

[PunchCardBoss]

I am using the one that came with the AX88U Pro

The voltage you are reporting seems right. A little over voltage is normal for a no-load condition.

The only way to really test the power brick is to measure voltage under load. That requires getting inside your 88U.

I have had power bricks show good no-load voltage but under load, the voltage crashes.

It is up to you if you want to check the voltage under load. You will need to measure volts inside the 88U, which is more involved. It is just a hunch on my part that your power brick might be faulty and be the cause of your unusual observations.

 

[Tech9]

Any ideas on what I could try next

If outside of store return period - call Asus Support, describe the issue, get RMA, send it back.

 

[glens]

The only way to really test the power brick is to measure voltage under load. That requires getting inside your 88U.

Or a "breakout box", as it were. Get yourself supply output voltage available outside of the router via a complimentary socket/plug combo. Certainly there's some old hardware laying around which could donate the necessary parts.

But gotta say, not being yet further into the thread than what's quoted, I've got the (early) impression this may be a faulty unit, worthy of RMA.

 

[glens]

get RMA

Great minds think alike? ;-)