We recently got a hAP AX S to test and play around with, and I noticed that it reboots every time we get to the upload portion of a speedtest. I have only tested on the 5GHz so far. I have tried using the included power adapter and others(same model) with no change. It's currently on 7.22.1. Anyone else see issues like this?
What the log says after reboot ?
What is your CPU usage while testing ?
Test with 2.4 and test wired connections.
What is rated output current of your adapters ?
It seems I have to power cycle it when this happens, so unfortunately nothing helpful in logs.
CPU usage seems to hit ~45% when testing on ethernet. It hits 80% during download on 5GHz, crashes too quickly to see CPU usage during upload. Highest I've seen on upload was 250Mbps before it crashes.
Wired connection seems fine.
2.4 seems fine, slow but that's just interference.
Using the included 24v 1500mA adapter and another identical one just to rule that out. I grabbed one of my 2.5a adapters from a 4011 to see if it uses more power(normally hovers around 8-9 watts under load.) No change except I did see 370Mbps on the upload using that before it crashed, but pretty sure it's unrelated.
I've also tried 7.24beta1 with the same, if not worse results, seems like it's crashing faster during upload tests.
What's in the logs? The usual suspect "kernel failure, probably power outage"?
Honestly, everything points out to some kind of hardware problem with wireless.
I would try to maybe netinstall the unit but if that doesn't help then I would return it.
Also seems to me like a hardware problem. You may wish to try out a different software version, just in case.
Honestly, this sounds to me like overheating. I would suspect badly applied thermal goo (for lack of a better term.) Of course, if you plan on returning it, it's impolite to mess with it...
I would replace it with hAP ax2 if USB port is not needed and if that is possible.
It's older device and doesn't have USB or SFP but if those features are not needed then it would be great replacement and I believe you would be happier with it.
I have been trying to get mine to work for the last few days and have exactly the same problem running 7.23.1. Tried 7.24beta1 but it didn't help. The problem is restricted to 5GHz. 2.4GHz works fine. So does a wired connection.
Interestly, one of the reviews on Amazon UK describes the same issue with two units on both wifi and wired (4 April 2026). Both returned.
"It is as easy to crash as running a speed test via any device connected to it - does not matter if its via cable or WiFi. It will randomly crash every now and then, too - in 24h both went down over 10 times."
I should add there is no obvious indication of anything overheating. The unit is cool to the touch and there are no "something's running hot" smells.
The overheating thing is just a guess, but for these kinds of devices, not a far-fetched one. The usual way is for the chips to lose thermal contact with the case that would serve as their heatsink, so the problem is in fact that the case doesn't get hot, but the chip locally does. Add the fact that applying the paste/goo is usually a manual process during manufacturing, and it's practically impossible to QC...
Really, it was just a guess.
You could download the (windows) bandwidth test tool from https://mikrotik.com/download/tools Legacy tools.
And run upload/download tests direct to the hap ax s. (While watching the system health cpu temp)
You can set a speed limit, so can ramp it up. (Tool is dodgy, but mostly works ok)
Just the typical "router was rebooted without proper shutdown" since I had to power cycle manually. It never comes back after a crash, it just sits there pulling ~3 watts and never reboots. Power light does stay on, though.
I've never seen this happen on my device ??
Well, this only shows how limited is your experience ... 
I wonder if it is a hardware issue confined to a faulty batch?
Mine does reboot with the message: “Router was rebooted without proper shutdown by watchdog timer”.
Unless I disable Watchdog, obviously.
Router typically pulls around 5-8w depending on what it is doing.
Would be useful to see configuration then.
Whatdog timer is something which has to be set specifically.
watchdog-timer is enabled by default.
Yes, I was going to say that Watchdog wasn’t set by me. I wiped the as bought config before setting it up.
Disabling Watchdog makes no difference. The router still crashes in the same circumstances. It just has to be restarted manually.
According to manual:
Software watchdog timer (mostly caused by hardware malfunction): the device can recover itself with a reboot.
hardware malfunction?
Hey! I recently bought the same device and got the exact same issue. Apparently for me the problem happens only with Wi-Fi. I made various speed tests on ethernet and it worked fine. Testing on Wi-Fi, on the other hand was very frustrating and caused the reboot almost every single time, even having only one device connected and using the device as access point only, no firewall, queues, etc. Since here there is basically no technical assistance for MikroTik devices I decided to return it.
So... Lesson learned here, avoid hAP ax S if possible...