After doing the update to Server 5.04 on my Yosemite server all of my websites stopped showing up (yikes!).
At first it looked like Apache wasn't running either, but even after restarting Apache from the command line, no joy.
I have read something about the ports changing, but all of the discussions seem to not apply to me.
Had the re-directed ports problem after updating to Server.app 5.0.3, but I was still able to access my websites by editing the URL or adding a "/" to the end. After updating to Server.app 5.0.4, more stuff was broken. No websites are available from the server, not its websites or others outside my little LAN. I can access websites outside my LAN from clients as usual, but none of the websites on my server are accessible.
My DNS, Wiki and Websites were all configured through the Server.app GUI -- nothing was configured in Terminal. That an upgrade would break things so badly is an outrage. Apple needs to fix this quickly.
5.04 Killed all my sites
