In this scenario we've added the following configuration to a Mobile Connect connection profile:
Add-VpnConnectionTriggerDnsConfiguration -ConnectionName "app_209" -DnsSuffix".subdomain.domain.local" -DnsIPAddress "10.0.0.1" -PassThru
With this VPN trigger existing, If we open any application and access the FQDN resource for example: srv1.subdomain.domain.local, the VPN connection doesn't get triggered.
This is an issue with the Add-VpnConnectionTriggerDnsConfiguration PowerShell command within Windows 10 RS1 build 14393 and is not an issue with the Mobile Connect client.
Mobile Connect for iOS, Android, macOS, and Chrome OS is not affected by this issue.
At this time there is no current workaround for this Windows 10 issue. Once a workaround has been identified this article will be updated to reflect the changes.