Nick, is there any chance you've disabled TLS 1.0 or 1.1 on the NPS server? I tried to do that in an office, but Win7 needed it for the RADIUS to function. I'm gong off the top of my head here, so I can't remember if there's a way to make Win7 use the higher level TLS settings. I went for the easiest solution of turning on TLS1.0 on the NPS server until we complete Win10 Migrations.