@sujitombase 

Hi ,
interesting solution.

Yes, in fact I tried to call the number of the sim and suddenly the connection was dropped and it was not restored.
As soon as I can I try your solution.

Thanks for now
Very kind

@Marceobeo 

I also think the solution is quite interesting and is there any special reason for that @sujitombase ?

Please also check the LTE band on the Archer MR600 to see whether it has changed to another one when the internet connection dropped;

--if it is, we have a beta firmware that could fix this issue due to the auto band switching;

By the way, did both wireless and Ethernet connections have the same issue?

@TP-Link 

I cannot give the answer immediately as the router is far from home and, due to national Covid restrictions, it will take several days to verify.
I am available eventually to test the beta firmware.

@Marceobeo 

Thanks again @sujitombase for the tip.
I did as advised and solved the problem.
I am amazed that such a problem, certainly not subjective, has not yet been solved for years by tplink.

Fortunately, there are still good users like @sujitombase who offer support.

Tplink, it is clear that you have to invest heavily in firmware development by not using customers as betatester.

@TP-Link 

UPDATE: the disconnection caused by a call on the router sim has been solved with the previous advice but unfortunately the router always disconnects by itself at random for no apparent reason.
The problem therefore remains.