Protocol Renegotiations when Connecting to ANY SMB file share from Windows 10 PC

Question

I am attempting to connect from a Windows 10 x64 Desktop client PC "Windows A" to the File Sharing services on a mac mini running macOS 10.12.2 Sierra server (UPDATE: the problem also exists when directly connecting to a Windows SMB server on the same network). This connection via SMB had worked just fine, however, starting about five days ago, I attempted this connection again and noticed that it failed.

Here is the current background:

1. Multiple things have changed in the environment since the last time that I know that this worked - at least two months ago: I have upgraded the server to 10.12 from 10.11, the server had a pending fan failure and multiple occasions of overheating until I realized how easy it was to swap out the fan on a 2012 Mac Mini, multiple pieces of software were installed on "Windows A".
2. I am using macOS 10.12.2 Sierra as the SMB and AFP file server.
3. SMB file sharing is enabled inside of the Server app on the Mac.
4. I can connect via a macOS client to the server with no issues using both AFP and SMBv2 (encrypted and not encrypted).
5. I can connect from my Surface Pro 3 running Windows 10 Desktop "Windows B" to the Mac server with no issues using SMB.
6. I can connect via the problem computer "Windows A" to the Mac server using SFTP, FTP, SSH, etc. with no issues.
7. I have attempted to connect from "Windows A" to another Mac OS Server (a Macbook Pro running macOS 10.12 sierra): the same problem persists.
8. I have also created a temporary local account on the computer, switched to it and attempted to log in using that account.
   • Wireshark shows the same process as with my main account: the "Windows A" user account is attempted first, then it prompts me for the manual account, which I enter. The computer then attempts to connect using the newly entered, correct account and fails with the same steps as in #11 below (repeating protocol renegotiations and timeouts).
9. For testing purposes, I have disabled all personal firewalls, antivirus, etc. on "Windows A".
10. I have ensured that "Windows A" is set to treat the network as private with all sharing enabled.
11. I have performed a wireshark capture of the conversation between "Windows A" and the Mac server and have noticed that it will by default attempt to use my Microsoft Account to authenticate to the Mac server, instead of asking me for a password for the actual local account. This happens when browsing to the machine.
12. If I manually specify a share (e.g. \serverIP\SHARENAME) in the file explorer, then "Windows A" will ask me for a password and will then attempt to set up a session with that actual local account. However, wireshark shows multiple syn/acks, then a keep alive request, followed by protocol renegotiations. This happens for multiple iterations while file explorer shows no changes for many minutes during this time.
13. I can connect with NO ISSUES via SMB and SMBv2 to a Windows file share at work with the same problem computer "Windows A". (UPDATED) But ONLY when connected to the work network over an SSL VPN. When directly on the work network, the connection via Windows file shares fails.
14. I have uninstalled multiple pieces of software including OpenVPN, Pulse Secure VPN, and some other small software packages that were installed over the last few months. The problem persists.

Any guidance on how to repair the SMB networking subsystem would be appreciated.

Thank you in advance for your help!