Its not very clear fromt he documentation that adding an ACL also affects internal virtual network communications as well as external endpoint access on the port defined. For Example: If you have two machines in different services connected via the same virtual network and are using the internal subnet IP for communication, the ACL will be applied to the traffic on the internal IP aswell as the external IP/Endpoint you apply it to, even if your not accessing the port via the external IP/endpoint.
After moving a few Windows Server Hyper-V hosts recently from one Virtual Machine Manager server to another, a couple of virtual machines started exhibiting some strange behaviour in regards to networking. So I break out trusty “ping” and it doesn’t report any problems. At that point the remote desktop session is working again so I lost interest assuming it to be “one of those things…”. After a couple of days this started happening more and more.
The sysprep automation within Virtual Machine Manger 2008 is a really nice feature which can help you deploy machines quickly and in a “set and forget” manner. If however you are unfortunate enough to not run your servers in the US locale you may have noticed that even if you change all the regional settings on your template target, after the sysprep has completed and produced a template any machine generated from it will be in the US locale.