Configure OpenVPN with IPv6 IPv4 on Synology NAS
If you want to access your NAS from the outside in the most secure way possible, VPN is the way to go (and all other options should ideally be turned off). Synology currently allows you to connect directly via IPv6 to the integrated OpenVPN server - but currently with a hook. We show you here the correct configuration of the OpenVPN server on the Synology and the access program Viscosity on the Mac for IPv4 and IPv6.
OpenVPN configuration on Synology NAS
The first steps for configuring the OpneVPN server for IPv4 and IPv6 are identical. The additional small settingsf for the IPv6 variant and the current restrictions we will show you in the following.
Important for the IPv4 use is that you have enabled the corresponding port for OpenVPN in your router! For the FritzBox we show you the corresponding settings here. DrayTek users should make these settings.
First go to System Settings Network on Synology and there to LAN and then to "Edit". Now select the IPv6 tab and set "DHCPv6-PD". Synology will then get the current IPv6 prefixes from the FritzBox or any other properly configured router.
Synology should then point out the new open port in its firewall.
Then you are done with the general IPv6 settings. The window should now look like this:
It doesn't say much, but that's completely correct.
Now you have to install the VPN server via the App Center, if you haven't already done so. Then open the OpenVPN and set a check mark at "Activate OpenVPN Server".
If you want to access not only the Synology itself but also other devices in your network via VPN server, check the box "Allow clients to access server LAN". The default port for OpenVPN is 1194, but you can also choose one from the unused range.
Do not forget to export the configuration file. Save on your drive and remember where you saved it.
Now you allow the use of the OpenVPN server for different users. To do this, switch to Privilege and set a checkmark for the corresponding users.
Done. Now you can use the OpenVPN on the Synology under IPv4.
To configure an appropriate client program on the Mac, we have chosen Viscosity. Read on here.
Additional OpenVPN IPv6 configuration on Synology NAS
If you now want to make the OpenVPN server on the Synology ready for IPv6, then you only have to set another checkmark at "Activate IPv6 server mode".
Then you select a prefix that is provided by your provider via the router.
Now the OpenVPN server is accessible via IPv6.
Important for the IPv6 use is that you have enabled the corresponding function in your router! For the FritzBox we show you the corresponding settings here. DrayTek users should make these settings.
The further settings for Viscosity, the OpenVPN client program on your Mac, we show you here.
Restrictions: The advantage of the new IPv6 address space is that there are so many addresses that each device can have its own public Internet address. A great feature! So things like DDNS and NAT (Network Address Translation) can be avoided.
In reality, however, things are unfortunately different: Since providers are constantly changing the prefixes assigned to reach devices over the network, we are in an even worse position than with IPv4: Since DDNS doesn't help, since each device now has its own address, after a prefix change, Synology is simply unreachable. Brave new world.
Synology knows about this problem and will solve it in the future (so that the OpenVPN server fetches itself a new prefix), but currently, depending on the lease time of your prefix, the connection is no longer reachable. Until this is fixed by Synology you can thank your provider.
However, there are some exceptions to this impractical situation: Business customers have the possibility to get fixed prefixes. Also for users of Vodafone cable customers there is the possibility to order the upload package: then there is a fixed IPv4 and IPv6 address.