Why does the VPN work for most of the company while one branch office, or a handful of remote staff, reports that it won't connect or crawls the moment they sign in? The difficulty with VPN troubleshooting is that the tunnel relies on every layer below it. If the laptop, home Wi-Fi, internet route, gateway, or security policy on either end misbehaves, the connection suffers. One complaint about a slow file share could originate at any of those points.