[Samba] connect Mac OS X 10.5.8 to Samba 4.9

[Matthias Leopold]

Hi,

I'm trying to connect a Mac OS X 10.5.8 client to a Samba 4.9 standalone 
server to no avail. I set the following on the Samba server:

lanman auth = yes
ntlm auth = yes
raw NTLMv2 auth = yes

According to the logs authentication works, but in the end the 
connection fails with

[2019/11/21 16:21:33.015930,  3] ../source3/smbd/negprot.c:419(reply_nt1)
   using SPNEGO
[2019/11/21 16:21:33.015961,  3] 
../source3/smbd/negprot.c:764(reply_negprot)
   Selected protocol NT LM 0.12
[2019/11/21 16:21:37.352679,  3] 
../source3/smbd/server_exit.c:237(exit_server_common)
   Server exit (failed to receive smb request)

The client displays some generic error message. Can somebody give me a 
clue what is needed by Mac OS X 10.5.8 clients?

thx
matthias