Hi Niklas!
There are 4 APARS (PQ54549, IC32139, IC32138 and IC32137)  with all about
the same text. I however cannot find any indication for a fix.
Anyway, here is the APAR text:

APAR= PQ54549  SER=                            IN INCORROUT
ANS1357S WHEN CONNECTING WITH NON-UNICODE CLIENT


Status: CLOSED                              Closed: 11/08/01

Apar Information:

RCOMP= 5698TSMVS    TIV 390 STORAGE RREL= R421
FCOMP= 5698TSMVS    TIV 390 STORAGE PFREL= F999  TREL= T
SRLS:      NONE

Return Codes:

Applicable Component Level/SU:
R421 PSY         UP

Error Description:
Once a unicode TSM client (V4.2.0 or higher Windows NT/2000
or V4.2.1.15 or higher Windows XP client)
has been used to connect to a TSM V4.2 server
with a given node name, that node name can no longer be
used by a non-unicode TSM client.  If you attempt to connect
with that node name using a non-unicode TSM client, you will

receive the following error:
.
ANS1357S Session rejected: Downlevel client code version
.
Any operation attempted by a non-unicode TSM client with this
node name, will fail with the above error message.  For example,
if the V4.2 Windows 2000 client has done queries or restores
for non-unicode filesystems for NODE1 to a V4.2 TSM server,
a V4.1 Windows 2000 client can no longer connect to
that V4.2 server as NODE1.

Initial Impact:  High

Local Fix:
None.  Contact support for assistance.


Problem Summary:
****************************************************************
* USERS AFFECTED: Non-unicode clients connecting to a V4.2     *
*                 server once a unicode client (V4.2.0 or      *
*                 higher Windows NT/2000 or V4.2.1.15 or       *
*                 higher Windows XP )  has been used to        *
*                 access that server using the non-unicode     *
*                 client's nodename.                           *
****************************************************************
* PROBLEM DESCRIPTION: ANS1357S Session rejected: Downlevel    *

*                      client code version  received after     *
*                      connecting to server.                   *
****************************************************************
* RECOMMENDATION: Install the PTF                              *
****************************************************************
Once a TSM unicode client (V4.2.0 or higher Windows NT/2000 or
V4.2.1.15 or higher Windows XP ) node has connected to a
TSM 4.2.0 or greater server (any platform) using a non-unicode
client's node, the non-unicode client node may no longer
connect to that server. A down level client message is
received.

Temporary Fix:


Comments:
MODULES/MACROS:   NONE

Problem Conclusion:
The TSM  unicode client (V4.2.0 or higher Windows NT/2000 or
V4.2.1.15 or higher Windows XP ) can now be used for queries
and restores, and a lower level or non-unicode 4.2 client can
still connect to the server.  As long as no unicode filespaces
exist, the 4.2 and above TSM server will allow a lower level
or non--unicode V4.2 client to connect to the server.  If any
unicode filespaces exist for a node, a unicode client will be
required to connect to the server.  If any unicode filespaces

exist for a node, and lower level or non-unicode clients
attempt to connect, the connection will be refused, and the
down level client message will be displayed.