Umbraco version 7.10.4

Hello, it seems that after the upgrade we getting a lot of the following errors:

2018-08-03 12:38:18,658 [P3720/D2/T34] ERROR NHibernate.Util.ADOExceptionReporter - A transport-level error has occurred when receiving results from the server. (provider: TCP Provider, error: 0 - The specified network name is no longer available.)
 2018-08-03 12:38:18,658 [P3720/D2/T34] WARN  NHibernate.Util.ADOExceptionReporter - System.ComponentModel.Win32Exception (0x80004005): The specified network name is no longer available
 2018-08-03 12:38:18,658 [P3720/D2/T34] ERROR NHibernate.Util.ADOExceptionReporter - The specified network name is no longer available
 2018-08-03 13:56:14,171 [P3720/D2/T40] ERROR Umbraco.Web.Scheduling.BackgroundTaskRunner - [InstructionProcessing] Task has failed
System.Data.SqlClient.SqlException (0x80131904): Execution Timeout Expired.  The timeout period elapsed prior to completion of the operation or the server is not responding. ---> System.ComponentModel.Win32Exception (0x80004005): The wait operation timed out
   at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)

We have a loadbalance scenario, and mostly server 2 gets this exceptions. The SQL server is reachable from this machine.

Any ideas what we could do/check? Thx, fabian