Having a look to my Samba logs on a 9.2 installation I can find several messages:
netr_ServerAuthenticate3: netlogon_creds_server_check failed. Rejecting auth request from client XXX machine account XXX$
The affected PCs are both W7 or W10 pro machines; appearently no side effects/error on client side because clients authenticate and browse network resourses; all of the clients have the corresponding registry tweaks applied.
Samba version currently running is 3.6.23-46el6_9 (x64).
Only noise ?