Does both machines have a valid hostname, that is with the same domain name ?
db.myserver.com Database server - or Master machine
web.myserver.com WPE/Web - or Worker machine
The master machine is fm.myserver.com and the worker machine is www.myserver.com
On the admin console status page I have the following:
Filemaker Host Name: fm.myserver.com
Web Server IP Addresses: www.myserver.com
Web Publishing Engine IP Addresses: myserver.com