Connecting ReadyNAS Duo from Internet

The answer to this depends on whether you have a v1 or a v2 duo. What firmware are you running?

At the bottom it says ReadyNAS Duo RND2000 v2 but in the front it is only ReadyNAS Duo. Im not sure but I think it is only v1
Firmware is RAIDiator 4.1.8

Ok, you do have a V1. That gives you more options for remote access.

The first step is to get a URL that will reach your home router. Generally your IP address will change, so a URL is much better. The way to get that is to sign up with a dynamic DNS server. There are some free ones (noip.com offers one). As part of that process, you will either need to configure your router to communicate with the ddns server, or install an app on your PC that does that. The PC method works just fine, as long as the PC is running when the IP address changes.

For web access, the best way is to use https, not http. With http your passwords, etc. are sent over the web in clear text, which is not a good thing.
To do this, you need to enable http on the shares you wish to access remotely. For a variety of reasons I use a non-standard port. To do that, you select a port and enter it as "port 2" in the https configuration (under standard file protocols). Any port over 49152 should be ok (meaning it should not collide with standard internet port usage). The standard port is 443. Whatever port you pick needs to be forwarded from the router to the NAS.

To use a non-standard port in your browser you put a ":xxxxx" after the url. For instance, https://nasurl:49152/shares

Getting a network share to work without ReadyNAS remote is more complicated, and depends on your version of windows. From the NAS point of view, you just enable WebDAV support for the share on the HTTP/S tab in Frontview (share listing). On the PC side, it can be very difficult to get this to work properly unless you install a third party WebDAV client. There are some instructions here: http://www.webdavsystem.com/server/access/windows

Personally I don't use WebDAV. Instead I have enabled FTP for my shares, and use FileZilla as my PC client. The Duo does support a secure FTP connection (FTP over Explicit TLS)

Okay thanks StephenB. I will try that :)

For some reason it won't connect to my nas from outside. I added a port 49876 to NAS station and forwarded it from my router.
I'm trying with HTTPS.

But it doesn't work... I have tried to connect it in browser with DDNS and my IP address.

Does it connect from inside if you use the same URL?

Also, did you remember to enable http/s for the shares you want to access?

The HTTPS does work when I connect to NAS drives internal IP so https shares are enabled. But when trying with my public IP address, it wont connect.
Do I have to enable HTTP also if want to use HTTPS?

You don't need to forward port 80 if you are using https. I don't forward it. Though internally, I can use either http or https.

My router will properly forward the traffic to the NAS (including my duo) even if I am using the public IP address/ddns name from inside my lan. I'm not sure if all routers do this.

You can use the following tool to check that port 49876 is open in the router: http://www.yougetsignal.com/tools/open-ports/
It should say open even if you are browsing from your PC.

Are you able to connect to other devices on your network by setting up port forwarding or is it only the ReadyNAS not responding.

I managed to get it working. I had to configure my router some more because the port wasn't open. Thanks!