Problem:
Connection from computer launched by WDS is dropped after connect to samba / nas / synology serwer.

Cause:
The problem is that within our environment, by default, Windows 7 required all SMB packets to be signed. Samba servers, however, do not. So there are two ways to fix this: turn off client signing in Win7 or add a flag to the smb.conf file in the global section as this: ’server signing = auto’. (we were using Samba 3.5.2).

For Windows 7, you can 'fix’ this policy by making it more lenient — going from requiring digital signatures to optionally using it if the server agrees.

Solution:
The local windows security policy changes are as follows: Start menu type GPEdit.msc Browse to Computer Configuration->Windows Settings->Security Settings->Local Policies->Security Options Look for „Microsoft network client: Digitally sign communications (always)” and change it to Disabled

You may also need to do the same for „Microsoft network client: Digitally sign communications (if server agrees)”. In theory this should be negotiated during the negotiate/challenge phase of NTLM but it may fail; NTLM doesn’t explicitly demand any real negotiation.

Source: http://serverfault.com/questions/261023/windows-7-client-attached-to-a-domain-connecting-to-a-samba-3-5-2-server