session dropped via VPN

the users have been experiencing problem with their session gto dropped and I trying to see how the connection behave so I issue the below command:

select s.sid, n.name, s.value from v$sesstat s, v$statname n
where s.statistic# = n.statistic# and
s.statistic# in (182,183,184,185) and
s.sid = 142 ;


and I got:

142 bytes sent via SQL*Net to client 2571
142 bytes received via SQL*Net from client 2120
142 SQL*Net roundtrips to/from client 43
142 bytes sent via SQL*Net to dblink 0


that's a very bad response, isn't it??? Is there any setting in the SQLnet.ora I can set so their session won't get dropped????

please advise.

These statistics show that the sessions were very short but they do not tell us much about why the sessions got dropped.

Do you have any other information about the sessions that were dropped? Did the users get any error messages at their workstations?