Local Adapter and/or VPN Tunnel Adapter becomes Unauth'd

Question

While off of third party VPN solution, problem doesn’t occur.
That said, when connected to active tunneling, authentication doesn’t present issues. Over a random non consistent period of time (typically a few times a day) the tunnel/vpn adapter on the OS becomes unauthenticated. Only after multiple refreshes and/or a reboot does this resolve, and thus represent.

Issue occurs across multiple clients and random machines (not all devices show these symptoms) and after talking with vendor, this seems to be a corner-case issue. To be clear, I’ve heard nothing through the grapevine, forums, colleagues, competition, etc. that would suggest otherwise. Plus, vendor has always been transparent and forthcoming in my experience. <<< directed at naysayers, in a noncombative tone.

After first hand troubleshooting in house and with vendor, we’d decided to add the LAN IP of the DC to the host record. That presented temporary remedy, however the problem represented.
We’ve changed routing configuration, tunnel configuration, DC configuration (only 1 DC) we’ve cut it in half to attempt to isolate… to no avail.

No issues with FQDN and IP resolution; until adapter becomes unauth’d.

Weird experience to note is that after adding the IP to HOST file (LAN IP not VPN IP) the VPN adapter cleared up but then presented the issue on the Local Adapter…

All research has pointed to a few things which are unfruitful in our attempts to resolve:

1. Update NIC drivers
2. Unjoin, rejoin domain
3. Check HotFix and patchTuesday issues (most recent from September 2022). There were presented issues with Windows KB but it was isolated to ARM, which were not running.

Obligatory partial key info:

Server 2012 R2 no issue
Windows 10 issue presented (same OS across client networks)

We’ve spent about a month working internally and with vendor engineering and we’re out of ideas, so I’m pinging this fine groups of folks for extra eyes-on and brains.

Happy to share more details.

Thanks so much!!