In two instances I have have a number of Mac Minis and iMacs that were not connected to the Internet but a local isolated LAN have their SMB:// shares refuse to connect, though they worked days or weeks before with no configuration changes.
After some testing I found that AFP:// and CIFS:// connections still worked using the same username and password as the non working SMB connections.
Since 10.9.x uses SMB by default now I wanted to figure out what was causing the issue instead of switching to AFP or CIFS as many have suggested.
Best Answer
Answering my own question since I had not seen this specific question answered.
After some log searching I finally found out that the issue was because the time on one of the machines was drifting causing it to become more than 5 minutes off from the computer it was connecting to and the server (computer connecting to) was displaying this log entry:
After finding this log entry I noticed and corrected the local time on the machines and the SMB connection via finder worked right away as expected.
The moral of this story is don't trust the Mac internal time without NTP backup; either via the Internet or a local NTP server.