Hello friends.. I'm having some issues with 2 app servers dishing out the below error for about 20 minutes and then it went back to normal.. I checked for network or server related issues and didn't find anything so I'm left at the DB or app level.

<log realm="mcx-server.server.session/10.116.102.100:58790" at="Mon Feb 22 17:45:31 CST 2016.833">
<session-start/>
</log>
<log realm="channel/10.116.102.100:58790" at="Mon Feb 22 17:45:31 CST 2016.833">
<receive>
<peer-disconnect/>
</receive>
</log>
<log realm="mcx-server.server.session/10.116.102.100:58790" at="Mon Feb 22 17:45:31 CST 2016.833">
<session-end/>
</log>
<log realm="org.jpos.ee.status.Monitor" at="Mon Feb 22 17:45:32 CST 2016.552">
<error>
<exception name="Cannot open connection">
org.hibernate.exception.JDBCConnectionException: Cannot open connection
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:74)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:29)
at org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:426)
at org.hibernate.jdbc.ConnectionManager.getConnection(ConnectionManager.java:144)
at org.hibernate.jdbc.JDBCContext.connection(JDBCContext.java:119)
at org.hibernate.transaction.JDBCTransaction.begin(JDBCTransaction.java:57)
at org.hibernate.impl.SessionImpl.beginTransaction(SessionImpl.java:1326)
at org.jpos.ee.DB.beginTransaction(DB.java:135)
at org.jpos.ee.status.StatusManager.touch(StatusManager.java:67)
at org.jpos.ee.status.Monitor.touch(Monitor.java:109)
at org.jpos.ee.status.Monitor.access$200(Monitor.java:34)
at org.jpos.ee.status.Monitor$MonitorTimerTask.run(Monitor.java:152)
at java.util.TimerThread.mainLoop(Unknown Source)
at java.util.TimerThread.run(Unknown Source)
Caused by: java.sql.SQLException: I/O Error: Read timed out
at net.sourceforge.jtds.jdbc.TdsCore.executeSQL(TdsCore.java:1093)
at net.sourceforge.jtds.jdbc.TdsCore.submitSQL(TdsCore.java:938)
at net.sourceforge.jtds.jdbc.JtdsConnection.setTransactionIsolation(JtdsConnection.java:2272)
at com.mchange.v2.c3p0.impl.NewProxyConnection.setTransactionIsolation(NewProxyConnection.java:701)
at org.hibernate.connection.C3P0ConnectionProvider.getConnection(C3P0ConnectionProvider.java:58)
at org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:423)
... 11 more
Caused by: java.net.SocketTimeoutException: Read timed out
at java.net.SocketInputStream.socketRead0(Native Method)
at java.net.SocketInputStream.socketRead(Unknown Source)
at java.net.SocketInputStream.read(Unknown Source)
at java.net.SocketInputStream.read(Unknown Source)
at java.io.DataInputStream.readFully(Unknown Source)
at java.io.DataInputStream.readFully(Unknown Source)
at net.sourceforge.jtds.jdbc.SharedSocket.readPacket(SharedSocket.java:850)
at net.sourceforge.jtds.jdbc.SharedSocket.getNetPacket(SharedSocket.java:731)
at net.sourceforge.jtds.jdbc.ResponseStream.getPacket(ResponseStream.java:477)
at net.sourceforge.jtds.jdbc.ResponseStream.read(ResponseStream.java:114)
at net.sourceforge.jtds.jdbc.ResponseStream.peek(ResponseStream.java:99)
at net.sourceforge.jtds.jdbc.TdsCore.wait(TdsCore.java:4127)
at net.sourceforge.jtds.jdbc.TdsCore.executeSQL(TdsCore.java:1086)
... 16 more
</exception>
</error>

This is related to the database setup. Hibernate simply delegates the connection request to the JDBC DataSource or Driver.
If there's a connection request failure, then you need to check the external connection pool, JDBC driver, and the database settings.