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n3ver
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Erratic device behaviour on WLAN

Sat May 01, 2021 12:04 pm

Hi everyone,

I'm a newbie and for some questionable reason I am using a hAP ac2 router.
My problem in short: a wireless device on the LAN can be available over cable and unavailable over WLAN at the same time unless pinged for some time from a wireless device.

Example
Devices:
1. Windows PC, wired connection
2. Android Phone, WLAN 5 GHz
3. ESP32-based IoT Device, WLAN 2.4 GHz
Please keep in mind that it doesn't really matter if device #2 is on 5 GHz or 2.4 GHz wireless network, because the problem persists in any case.

The bamboozle:
If I ping the device from PC, it's 0% packet loss, everything's OK.
Then I try and ping it from the Android phone, and it returns "Destination host unreachable". Even if it's being successfully pinged from the PC at the very same time.

Then some magic happens.
If I keep pinging device #3 for some time from the phone OR if I send a number of requests from other wireless IoT devices to it, it starts responding and stays available for some time.
I can't tell for how long it stays that way, but it will turn unresponsive in some time. In that case I'll have to ping it to life again.
I've noticed that if it's unavailable from the phone, it's unavailable from other WLAN devices either and vice versa.

I couldn't find any requirements as to post the config file on topic creation, so let me know if it's necessary, I have it ready.
 
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mkx
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Re: Erratic device behaviour on WLAN

Sat May 01, 2021 12:32 pm

Anything about erratic device in logs? Copy-paste output of command /log print (run it in terminal window) to a text editor and search through logs for device's MAC address and/or IP address.
 
n3ver
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Re: Erratic device behaviour on WLAN

Sat May 01, 2021 7:30 pm

Hi mkx,

Actually, there are multiple identical devices on the network that work this way, I had just simplified the setup in the original post for clarity.

This is the example output that I get for all the wireless devices that give me trouble, I just shortened it down to one.
18:55:53 system,info router rebooted 
18:55:58 wireless,info AC:67:B2:2B:71:F0@wlan1_2.4: connected, signal strength -51 
18:56:02 dhcp,info dhcp1 deassigned 192.168.0.250 from AC:67:B2:2B:71:F0 
18:56:02 dhcp,info dhcp1 assigned 192.168.0.250 to AC:67:B2:2B:71:F0 

That’s it. Not sure if this is helpful. However, there’s some more info that I have noticed meanwhile:
- If I ping a wireless device continuously from another wireless device, the connection between them stays stable as long as the ping is going.
- First packet when pinging from the PC (over Ethernet cable) sometimes fails or returns high latency (I’d mentioned previously that the cabled connection is always fine — it’s not, but it’s much less of a trouble). Perhaps it’s about ARP table or something address-related. As if Windows PC has all the addresses stored handy, and other devices do not, so they have to resolve it each time they need to make a request which results in temporary packet loss.

Just in case: if I replace the router with a simpler one the problem is gone, so the issue is more likely to have something to do with Mikrotik’s configuration, and not with the devices.
 
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mkx
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Re: Erratic device behaviour on WLAN

Sat May 01, 2021 8:51 pm

There are a few settings which might affect the way wireless clients behave. I suggest you to re-post about the problem in forum section about wireless. There are a few users very knowledgeable about wireless woes but they might not follow topics in this part of forum.

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