MacOS – Yosemite when logged in will not connect to internet (but during system recovery mode will)

Since I wrote this post my Internet problems seem to have gotten a lot better. As far as I can remember, I only made two more changes. I can't say for sure which one of these helped, or if either them helped at all and maybe there was some other factor I'm forgetting, but they may be worth a try:

1. I changed my DNS settings to use Google's Public DNS. I can't remember what they were previously, but I definitely remember playing around with my DNS settings a few months ago so this may have been the culprit.

2. I changed the automatic MU settings, following the instructions on this page.

Hopefully someone will find one or both of these to be helpful!

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:

<date> <time> kdc[80]: Too large time skew, client time <time> is out by 356 > 300 seconds -- <user>@LKDC:<SHA1>

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.