If the frontend is going to reside on the web then both the front end and the backend have to reside on the same server. This is my understanding at least. Because the path to the backend has to be that, a path not an url. Frontends require you to be able to link the tables. Henceforth, if you try to link your frontend, you will see no way to look on the web. But if the frontend is on the same server, than you would be able to see the backend.
Now, on networks you can have it spread over multiple servers. This is what I currently do. I have backends reside on one server then the front end is linked, because you can go through my network places (win 2000.)
On another note, you can put the frontend on a webserver and have the backend reside on a DB server sucha as Oracle or SQL Server. I also have this running, but this requires the tables to be in sql (in my case.) The frontend has to be reconstructed using ASP, JASP, CFM, or something of the sort.
The only way that I could see your situation working, would be if the web server resided on a network that your frontend could connect too. The_Doc_man is very knowledgable about networks as well. So, if I have said anything in error, many apologies, this is my current understanding. I am always learning.