Windows 8.1 Networking – How to Fix UNC Path Access Error Code 0x80070035

As an answer to the re-worded question:

Most likely your problem is the service is running as a system user, and not a network user or a user on the remote machine. In a domain you would want to either allow everyone / anon users too, or preferable create a service account on the domain / network and run the service as that account

Running HVRemote helped to elucidate the cause, and it turns out the firewall on the client was misconfigured.

The Dragon is protected by Norton Internet Security. While I had a firewall rule explicitly granting access to the server, it was placed at the bottom of the list of rules, so it did not have the intended effect and DCOM communication was blocked by the firewall anyway. After moving the rule to the top of the list, I am able to reach the server through Hyper-V Manager without any issues.

To clarify the issue, here's what the online documentation for Norton Internet Security says:

The Smart Firewall processes Traffic rules before it processes Program rules. For example, when there is a Program rule that allows Internet Explorer to access Internet using port 80 with TCP protocol and a Traffic rule that blocks TCP communication through port 80 for all applications. The Internet Explorer application cannot access the Internet as Norton Internet Security gives precedence to Traffic rules over the Program rules.

Within the list of Traffic rules, rules are processed in order of appearance, from top to bottom. Program Rules entries are not processed in order. The rules within each Program Rules entry, however, are processed in order of appearance, from top to bottom.

For example, you have a Program rule for the Symantec pcAnywhere application that blocks the use of the application with any other computer. You add another rule for the same application that allows its use with a specific computer. You then move the new rule before the original rule in the program rule list. Norton Internet Security processes the new rule first and lets you use Symantec pcAnywhere with that specific computer. It then processes the original rule and prevents its use with any other computer.

As a happy ending, here's the openSUSE installer running on a VM hosted on the Wyvern and displayed on the Dragon: