Precision 3591 - Periodical issue with connection to internal/external services

Hello all, 

We got the complaint from user with Precision 3591 machine, having periodical interruption with connection to both internal/external services. The situation is following - user can work normally until a moment where he lost a connection, and after the restart of laptop, everything starts working again. After information that this is happening just when they are connected via Ethernet when in the office, and checking what could be the cause of issue, we noticed that there is a possibility that "power saving" mode on the machine can cause this. Our theory is that since they are using applications that put a heavy load on the machine, where CPU is mostly going to 80%, this is causing for power saving mode to shut the services or Ethernet adapter itself and shut the connections.

Can you please give your advice in this case? Were there similar issues before?