Heterogeneous RPC connection failing

I keep getting the message below from a connection to SQL-Server.

My Oracle is on a server behind a firewall which for some reason is timing out.

I get the following message when retrieving a couple hundred thousand rows from the SQL-Server.

declare

*

ERROR at line 1:

ORA-02050: transaction 182.59.3247 rolled back, some remote DBs may be in-doubt

ORA-28511: lost RPC connection to heterogeneous remote agent using

SID=ORA-28511: lost RPC connection to heterogeneous remote agent using

SID=(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=localhost)(PORT=1525))(CONNECT_DAT

A=(SID=dg4msqlStg)))

ORA-02063: preceding line from SSSTG

ORA-06512: at line 26

My sqlnet configuration has the following configurations