You can resolve this issue by manually correcting the Windows Firewall Rule created for each of your AOS instances:
1. 1n Windows click Start -> Administrative Tools -> Windows Firewall with Advanced Security” or run WF.msc
2. Click on “Inbound Rules”
3. Locate the rule starting with the words “Dynamics AX 5.0…” and double-click on it to open its properties
4. Click on the “Programs and Services” tab
5. Correct the text field specified for the radio button “This program” by adding the missing “.exe” extension to the path to your AOS service application, ax32serv.exe, and click on OK.
For example on my test system I had the path specified as “C:Program FilesMicrosoft Dynamics AX50ServerContosoTransDemoDataAx2009BinAx32Serv” and I modified it to “C:Program FilesMicrosoft Dynamics AX50ServerContosoTransDemoDataAx2009BinAx32Serv.exe“, and then after a couple of seconds I was able to access the AOS service from a remote AX client/.NET Business Connector