I was recently asked for some assistance in troubleshooting a FileMaker Server 15 installation issue where the user could connect to the FMServer_Sample file, but was not able to use the FileMaker client to upload databases.
They received a generic “Connection failed.” error as shown below:

The user had set up a Windows firewall exception for their own IP address that allowed all traffic through and we were able to use Wireshark to view that traffic was indeed reaching the FileMaker Server. We tried placing a file directly into the Databases folder on the server and were able to open and connect to that file just fine.
We were connected to the Admin Console on the server itself, so on a whim I asked, “Can you connect to the Admin Console from your workstation?” Turns out the answer was no, we received a 404 error trying to connect! I thought that was a bit odd so we took a look at IIS Manager and I noticed something right away — there was no sign of the URL Rewrite Module in IIS! I knew FileMaker Server used the rewrite rules for the Admin Console and a few other things like WebDirect, but wasn’t sure if it was used by the client itself (hint: it is). We installed the IIS URL Rewrite Module, try to “repair” the install and run the deployment wizard again, but were not able to get FileMaker to create the rewrite rules. I suggested the user uninstall and reinstall FileMaker Server, but that would have to wait until the next day.

In the meantime I fired up my Dev copy of FileMaker Server to test a few things out. I started by disabling all of the rewrite rules created by FileMaker and then re-enabling them one-by-one to try and figure out which rule was used to upload files. It didn’t take long until I found the offending rule; the “fmws” rule, as it turns out, is used to rewrite incoming database upload requests to the proper location.

Without this rule in place, the server didn’t know what to do with the request and simply rejected it. Now, some of you may be wondering why the IIS URL Rewrite Module wasn’t installed; doesn’t FileMaker Server install this during installation? Normally, yes, it does. In our environment however, servers rarely have access to the Internet, so the FileMaker Server installation is not able to download and install the ARR package, we have to do that manually. The user had installed ARR, but not the URL Rewrite module. I’ll have a post up in the next few days to detail installing FileMaker Server while being disconnected from the Internet.