Directory Synchronization Error

Hi everyone!

I am currently trying to sync my on-premise Active Directory (hosted on Windows Server 2012 R2) with Azure's AD using the AD sync tool. However, I cannot get past the "Windows Azure Active Directory Credentials" step.

I have two accounts (for the sake of this post, let's call them A and B), both of which are global administrators on Azure. When I enter the credentials for account A, the sync tool insists that "The user name or password is incorrect" even though I can log onto the Azure portal with those exact credentials on my browser. It may be worth noting that account A does not require additional verification to sign on.

Account B has additional security verification and thus I created an app password for the sync tool (this feature is not present on account A since it does not require verification). Whenever I use the generated app password, I am greeted with the configuration error: "Unable to establish a connection to the authentication service. Contact Technical Support." Anything else in the password field will return "The user name or password is incorrect", leaving me to assume that the app password is valid, but my request is just not going through.

Each log-in attempt with account B and the app password has generated the following errors in my Server Manager logs:

So far, I have tried:
- restarting my server
- re-installing the sync tool
- clearing my DNS cache
- restarting the Azure sync service
- disabling all firewalls 

If anyone could help me interpret the errors or even provide me with a possible solution, I would greatly appreciate it!

Best,
Jason