A client has a Mac mini running Yosemite 10.10.5 Server. It serves a small workgroup of Mac users in an otherwise Windows environment (Windows PC's on a Windows server domain). I've left the server alone, but now that the Mac Pro's have been updated to Sierra, we want to update the server. BUT, ever since updating the Mac Pro's to Sierra, we have issues with SMB authentication (doesn't remember passwords in keychain) and even AFP shares not always connecting. I thought bringing the server up to current 10.12.3 Sierra might help alleviate that, but now I've also read that Sierra has SMB issues. So the question is, should I just update the server to the latest El Capitan server until 10.12.4 is released, or bring it fully up to date with 10.12.3? Recommendations?