In theory, it should be possible. First, you should post what's currently in your routing table:
Example of mine (I use an PPPOE connection to connect to the internet, maybe you don't, but at least you should see there some interface for your VPN connection while active).
- Code: Select all
DiskStation> route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
80.200.x.x 0.0.0.0 255.255.255.255 UH 0 0 0 ppp0
192.168.24.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
0.0.0.0 18.104.22.168 0.0.0.0 UG 0 0 0 ppp0
By default, all traffic will pass through your own default gateway. However, if you define static routes for the target ip adresses you want to download from, it should be possible to tell your diskstation to use the VPN tunnel.
Maybe there's a way to route all traffic thought the tunnel, but this will be some kind chicken or egg problem:
You need the default gateway of your own router/isp to access the internet, but you want to tell the diskstation to use the tunnel to route all trafic through. I don't know how you can combine that to make it work.