I have 2-machine deployment on Windows 2012 servers. I was running 14.0.2 today without issue and made the mistake of using the FMS 14.0.3 updater. It ran fine but when I came back up after the update, two key features were broken.
1) WebDirect stopped working. When I checked in Wed Admin the Web Server was grayed out even though it still showed the proper IP address. The Web Publishing Engine was switched off. I could turn it on and the status would change to green but nothing could get the Web Server to come back. So all WebDirect access was broken.
2) External access to the Admin Console was broke. I could however still get into the Admin Console while directly on the Master.
Filemaker tech support advised that the second condition is a known issue with the 14.0.3 patch. It was not aware of the first issue but felt they are likely to be related.
The only solution is to do a complete uninstall on both the Worker and Master. I took the chance and installed the full version of FMS 14.0.3 after the uninstall and thankfully it did work.
My advice is do not use the 14.0.3 patch until Filemaker sorts it out. If you do be ready to do a full uninstall and reinstall if it doesn't work. Make sure you have a download of the full 14.0.3 file from your licensing links ready.