For Samsung device running ELM Android+ device agent, you should be able to upgrade the device remotely by using a file-sync rule to get the new device agent apk file downloaded to a device directory such as %sdcard%\Download\, and configure the post-install script 

    install %sdcard%\Download\your_new_agent.apk 

in the "advanced" tab of your file-sync rule, to be executed only when file has been transmitted.

Can you successfuly start a remote-control session on other device brand/model  with your current MobiControl server?

If not, have you ever successfully start any remote-control session with any device (of this or other brand/model) with your current MobiControl server?  Has there been any server upgrade or network reconfigurations recently?

Have you tried using a device agent of different version/build number on your X-Cover 4s (SM-G398FN) device?

Hello Alexey Stepanov,

Thank you for your post, please upgrade MobiControl agent to the latest version.

As most the issue related to remote control is been resolved in current version of agent (14.7).

Regards,

Thanks for your answer, Raymond

At the moment we are trying different build versions of agents for 13th soti, because we can't move yet our devices to 14th version of SOTI.

Unfortunately, with no success

For Samsung devices using Android Plus devive agent, it's perfectly OK to use v14.x device agent even when your Mobicontrol server version is still v13.x.

With agent version 14 now I can use remote control perfectly! But it was installed manually via apk.

How can I upgrade agent to version 14 on my server which is 13? Because I have few devices already deployed with older agent version.

Thanks for your help!