How to create Encrypted Home Directories with Synology NAS

1. Provided that there is no firewall preventing the outgoing VPN connection of your NAS you should be able to connect the NAS to a VPN network using OpenVPN. Synology also supports PPTP but I'd recommend not using that.

2. The NAS will also still be able to communicate with the local machines while connected to the VPN.

3. Finding a VPN Provider for this will not be that easy as most of the VPN providers are - as you already found out - more like anonymizer services. Maybe someone else has a tip on this. If not it might be easier and not so time consuming to simply setup a VPS to host your VPN?

Try to either reset the account on the NAS in the domain or delete it. Sync the AD DCs. Make sure DNS on the box defined as one of the DCs.