Studio shows as unregistered.
Ping works fine.
VDA registration health check tool passes all the tests.

Error: Exception System.ComponentModel.Win32Exception (0x80004005): The Security Support Provider Interface (SSPI) negotiation failed.

Clearing the Security event log should allow the negotiation process.

OR

Setting the CrashonAuditFail set to 1 on the VDA

HKLM\SYSTEM\CurrentControlSet\Control\Lsa
REG_DWORD CrashOnAuditFail = 1
 

---

Problem Cause

The issue is due to failed authentication which is due to the fact that the Server's Security event logs gets full.
In this state only administrators can login.