Pursuant to this issue:
Can't connect to VPN on 14.04 LTS
So the last time my VPN client worked was ~20 days ago. I checked with the ISP and they say "No problem", I checked with my company's help desk and they say, "No problem", I've checked and re-checked my credentials and there's no apparent problem there. In any case there is a specific error when credentials are wrong and I'm getting a generic one. "Connection failed".
My current theory, which I want to test, is that it's a bad update. I want to revert all updates back to 20 days ago and then step forward so I can find out exactly which version or series of updates is causing trouble. How can I do this?