Project Sharing Network Protocol when using SMB on Mac OSX

SMB on Mac OS has been a moving target, but it is getting better. It is more mature with Mac OS 10.10, 10.11 and beyond.

NOTE: AFP is now deprecated as of 10.13. You should only use SMB.

Some background information on SMB 

SMB is Microsoft’s proprietary network file sharing protocol. Most versions of OS X prior to 10.7 relied on an open-source implementation of SMB called Samba for accessing Windows file shares and sharing files with Windows clients. When the licensing terms for Samba changed, Apple had to develop their own SMB implementation. Apple has been struggling with it and it is still not as stable as it should be. 

Possible Issues with Project Sharing 

• We have not seen any issues with SMB on Windows clients, but have seen issues saving from Windows SMB to Mac OS X 10.11, these issues are not present when saving to 10.10 or 10.12. 
• On Mac OS X, we have seen ACL permissions problems with SMB2 and SMB3 with certain versions of OS X (early 10.9.x). 
• We have not seen the same issues with AFP or SMB1 (“CIFS” protocol prefix). 
• Many SMB issues are related to a mix of SMB protocols between clients. 
• SMB3 (now the default for Mac OS 10.10) could have problems when interworking with machines that don’t have full support for SMB3. 
• Much better results can be expected when all machines were on the same SMB protocol version. 

• We have seen problems mixing AFP and SMB clients for the same share

For Project Sharing, our recommendation is: 

• Use SMB for both Mac and Windows.
• Use the latest version of macOS. 
• Use the same SMB version that works well for all clients. 
• Use the newest OS X version. 

• SMB has version negotiation, so servers can be set to negotiate only up to SMB2 if there are machines that don’t fully support SMB3.

• Never mix AFP and SMB access to a share.

Following these recommendations should provide a better experience. 
We are all hopeful that Apple will improve the stability of its SMB protocol at a faster pace now that they have made it the default protocol for Mac OS.