@terziyski  thanks for trying to help me. 

I tried using a range extender even though the line is good, I disabled the 5 ghz connection but nothing changed. 

Later I changed the following parameters: adding address reservation to the boiler wifi module,Address Lease Time to 2880. 

It seems that this way less time passes between disconnection and reconnection. I started changing these parameters because, connecting the boiler module to a mobile phone in hotspotting, there is no disconnecting. Therefore I thought this problem could be linked to some router settings. 

terziyski wrote

  @Serse 

 

One possible reason could be the distance between the MR200 and the boiler module - here are some advises for placing the router.

Another reason could be the using of Smart Connect feature - most of the IoT devices use the 2.4 GHz band, so disable it and test how it goes.

what else can I try? 

  @terziyski nothing changed.

Hi  @terziyski .

I tried your solution and modified also the channel and its Width - no auto but only 40Mhz.

After one day, there was no disconnection.

Thank you very much for you support.

Goodbye.

terziyski wrote

  @Serse 

 

Set MR200 wireless mode to  802.11n only for optimal performance.

I would experiment with different static wireless channels to check if there's an improvement.- the wireless channel may interfere with LTE frequency band.

If nothing help you could contact your local support for further assistance.