@Hoggorm 

I'll give you steps how to set remote connection to NAS, after each step reply with confirmation it is checked or done, and I'll provide you with the next step.

Step 1. Configure Synology NAS to receive its IP address from DHCP.

If you had to make that change, reboot NAS (just in case). Then, check that you see Synology NAS in Deco app, in the list of devices connected to Satellite Deco (Office).

Hello Alexandre,

I have QuickConnect access to the NAS from my home and I can confirm that DHCP is configured.

I appreciate you effort however I do not have full access to all systems all the time. Remember this setup is at a family members house, not mine.

I can't travel to her between all steps you intend to provide.

  @Hoggorm 

Remaining steps require configuration changes in Deco mesh and in ISP Router. It is possible to do Deco changes remotely through Deco app.

On ISP Router you will need to configure port forwarding for NAS after we are done with Deco mesh changes. What is your plan to do that: do you have remote access to ISP Router?

  @Alexandre. 

I will need to visit her house when doing those steps. I will have full access to both ISP router and Deco iOS app there.

I assume I need to port forward in the ISP router the relevant ports to one of the two Deco devices? And then in the Deco iOS app apply port forwarding to the NAS?

The latter is already done as far as I know, but it did not work. Therefore I assume I also need to open relevant ports in the ISP router. The problem is to what device I should forward them to as the NAS itself does not appear in the connected clients list of the ISP router. Two Deco mesh devices does however.

  @Hoggorm 

OK, so here are remaining steps and make sure you do them locally, so that you can undo changes right away if something goes wrong.

Also, you didn't confirm you see NAS in Deco app connected to Office Deco by Ethernet, if you do not - I suggest not to proceed further until finding why is that.

Step 2. Configure Deco mesh to run in Access Point mode. Switching a Deco to Access Point (AP) Mode

Verify that you now see NAS in the connected clients list of the ISP router. You should.

Now that you do, remaining steps should be obvious, but listing them anyway, could be of help for others who may found this topic useful.

Step 3. Using ISP Router IP reservation feature, reserve IP address for NAS in ISP Router. This step is optional, but highly recommended.

Step 4. Configure NAS port forwarding settings on ISP Router. Now that NAS is just a client for ISP Router, that task should be familiar to you.

Done.

Hint: now that you run Deco mesh in Access Point mode, you can wire Synology NAS to any Ethernet port of home network, including directly to ISP router. That's what I did with my Synology NAS.

This could be more reliable link for remote management and for home network-wide access than through Satellite Deco on WiFi backhaul, and won't depend on Deco mesh.

  @Alexandre. 
 

Thank you.

Yes, I do see the NAS already connected to the Office Deco. I see it connected in the Deco iOS app and I can see its IP.

My concern is regarding changing mode to access point mode. As this is not my own system, wifi and network, but a family members setup. What happens when I change to access mode? What mode is it now? Maybe some devices she already has connected is dependent on the mode it is in now?

Can I not open a port to the Deco system from the ISP router only?

The Deco iOS app has port forwarding settigs in the Advanced settigs.

Your suggestion does not utilize that at all?

  @Hoggorm 

Start with this: What’s the difference between Access Point mode and Router mode on the Deco?

Short summary: if they only need WiFi coverage from Deco mesh and not content/bandwidth management features, it is safe to switch Deco mesh to Access Point mode from its default Router mode.

What you have now is double NAT: router (Main Deco) behind the router (ISP Router). Double NAT is pain in the neck when comes to port forwarding, also may cause other issues. The simplest way to get rid of double NAT is to have Deco mesh run in Access Point mode. 

Note that if you find they do need features missing from Access Point mode, it is easy to rollback Deco mesh to its default Router mode. Then, of course, you'll be back to square one with remote NAS access.

You should at least try my steps. They can be easily rolled back.

  @Alexandre. 

Yeah, I got you. I can hopefully try this either tomorrow or tuesday.

If I understand the link you provided correctly all devices need to be in AP mode for this to work? Or can I choose to have only one, Office, in this case in AP mode?

As far as I know there are three or four Deco devices in the house at present. One is ethernet wired to the ISP router. The other three are located in different parts of the house.

As far as I can understand the one connected to the ISP router feeds data to/from the other three. Is this correct?

Can the one connected to the ISP router remain as wifi router or do I need to change this one as well to AP mode?

  @Hoggorm 

Deco mesh Router/Access Point mode is global setting, applies to all Deco nodes in the Deco mesh.

In default Router mode, Deco mesh provides WiFi mesh, Main Deco runs as a regular router performing LAN management: IP address allocation, port forwarding, etc. 

In Access Point mode, Deco mesh provides WiFi mesh, delegates LAN management to ISP router. Every device connected by WiFi or Ethernet to Deco mesh will be client listed in ISP router, also you'll see all Deco units as clients listed in ISP router.

>As far as I can understand the one connected to the ISP router feeds data to/from the other three. Is this correct?

This is correct. This will continue in Access Point mode, but instead of managing network Main Deco will be not much more than pass-through for traffic coming to/from Satellite Deco.

  @Alexandre. 

I understand. Thank you.

I believe she now has three or four different SSIDs in her home based on what Deco a device is connected to.

After placing the system in AP mode, will there be only one SSID seen then, or will all Deco devices still transmit their own SSID?