GL-B1300 Wifi unstable

Is it just me, or is the wifi of the GL-B1300 very unstable?
I have a mesh configuration with two B1300 with software V2.07 (latest).
Two different smartphone loose connection at the same time no matter where it is (near or far to each of the two routers). After some time (usually ~10 sec) the wifi is up again.
This is very annoying!
Edit: I checked wether the used Wifi channel is already occupied through Wifi Analyzer.

When did you buy the B1300?
The latest firmware version of B1300 is 3.027.

My mistake. Of course I have 3.027. I made a typo.

Do you have any other configurations? Such as repeater

Even without the repeater I have this problems.
Can I give some more hints?
Config file?

Are you using 2.4G or 5G wifi?

Both. 2.4 and 5Ghz are enabled.

I mean, do you mean 2.4G wifi is not stable or 5G wifi is not stable, or both?

Is your smartphone connected to 2.4G or 5G wifi.

It is connected via 2.4 Ghz

Can you try connecting your devices to 5G WiFi ?

I can not modify the wifi settings in mesh mode.
So I disabled the mesh, rebooted the main node to enable both 2.4 and 5GHz on the main node.
Then I re-enabled the mesh.
Now I am connected via 5GHz and see the same problems.

You can try to slow down the wifi speed to improve stability。

How can I slow down the wifi speed?

Set it up here