I have never seen similar message in any project/device since working on Soti MobiControl v9 and later solutions.   This message is more likely to be related to the firmware and/or some proprietary settings of this Handheld Nautiz X41.

Please provide more details. E.g. server and agent version & build numbers, enrollement mode, firmware version, deployed MDM policies related to Wifi/cellular communications, actual states of Wifi/cellular network before and after this message shown on your problematic device, message in the device log or Mobicontrol server log files, etc.

Server version: 14.1.4.1693

Agent version: 14.5.5.1023 build 1023

Enrollment mode: Android Plus

• No MDM policies or restrictions related to Wifi/cellular communications in these devices (same prompt appears on all these device models).
• Prompt appears when WiFi network is unreachable or removed from settings. Before that the mobile network's icon is on and the ISP name is shown. If I press OK the devices starts using mobile network. However the prompt is annoyingly popping up if the WiFi has a bad signal and the device connects to it randomly.
• If I put the WiFi off from the device, also the mobile network shuts down automatically.
• There is no logs related to this issue.
• Not sure what firmware version you are asking?

From your description, the root cause of the problem is the unstable poor signal of the Wfi network which your device tries to connect to.  As far as I know, all Android device firmware will by default try to use Wifi for data traffic when available.  There might be software codes that detects many consecutive broken Wifi connections within a short period of time before it will generate error code or message on the device screen, to prompt device end-user to use cellular connection instead of the poor (but default ) Wifi connection any more.

I believe there won't be such message if the Wifi access-point hardware can be enhanced (eg. configured to increase output signal level or improved antenna, or relocated to more favourable location relative to where you do your test, etc.).   I don't think there is any MDM solution that has configurable options to disable this type of message, as insisting the device to connect to a poor Wifi connection is a stupid stubborn choice.  If I am the device end-user and find out the Wifi access-point/hot-spot is consistently not good enough, I will just remove such Wifi SSID/credential to avoid using it any more when I come to the same place.

I'm not sure if you can rid of this message when doing following, but in general it should work.

You can define a out of contact rule and there to enable mobile data if connection is lost.

But as i just said, don't know about the notification and the other way around should be manually.

I tried the out of contact rule and it activates the mobile network after one minute (that's the shortest possible activation time). However the notification still stays on the screen.

Don't waste your time.  The root cause of your problem is the unstable and weak signal from the Wifi, not the device firmware.  Even if you can successfully bypass the message prompt with some out-of-contact policy script, the unstable signal level just means that your device will repeatedly switches between Wifi and Cellular connections at very high rate, which likely render the short-lived connection virtually unusable for real-life apps because the IP address of your device is changing all the time.

If you cannot replace/enhance the Wifi hardware and really want some software approach to fix the problem,  you probably need a smart customized app that interacts with Mobicontrol device agent with smart algorithm that adapts in real time according to available Wifi SSID/MAC's (e.g. to act only when your weak Wifi access point is around) and their RSSI signal profiles in a moving time window.

Even if the signal is unstable or the device has no connection to internet, our app would work. During that time it saves everything locally and updates them to server when it's possible. The notification however prevents the user to use the app properly. And even if the notification would come only once a month, I would prefer like it is in pretty much every mobile phone and in our other Zebra devices, where it connects automatically to mobile network if the WiFi is unreachable.

But I think you're right that this is related to firmware or some settings of Nautiz X41 and can't be solved from MobiControl.

Thanks for your help Raymond and Rafael!