Unable to reach NAS via local IP address but able to reach it via public IP address

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Unable to reach NAS via local IP address but able to reach it via public IP address

Post by m.bagattini » Sun Sep 13, 2020 5:23 pm

So I'm in this strange situation.

My NAS (TS-251B) is connected to my LAN, replies to ping at It is seen by Qfinder. I have the dynamic DNS in place and my router redirects correctly to the NAS local IP. So, if i connect to https://nasname.myqnapcloud.com I can reach it and configure it. I can also reach it to https://<current public IP> but, as expected, I get the mismatching certificate alert in my browser.
What I can't understand is why I can't reach it via or https://nasname; if I have no internet, I can't connect to the NAS. Qfinder lists the NAS but can't access its configuration too. Windows can't find its shares if I try browse via Explorer and NAS isn't listed under Network.

I'm pretty sure this is a recent problem, I was previously able to do all of that. As a safety measure, I wanted to close my outside access so that's when I discovered this issue.

I'm not able to track back to something I did that broke the configuration; I've recently reset my router but I'm pretty sure the only setting I had on it was the port forwarding. What I did that may be related was the installation of the container station and addition of a docker image for pi-hole. I'm not really a networking expert so I don't know, maybe now who's responding to my connection request to the NAS admin page isn't the NAS anymore but some other service? It's the only thing that came to my mind. I see some configs under virtual switch but I don't want to touch there since I don't really know what I'm doing.

Any suggestion would be really welcomed!

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Re: Unable to reach NAS via local IP address but able to reach it via public IP address

Post by oyvindo » Mon Sep 14, 2020 2:25 am

Why do you use HTTPS to log on to your NAS inside your LAN? If you LAN is behind a NAT router, there is no need to use HTTPS, unless you have som very specific requirements. And if you do, you have to create (or buy) certificates and have them registered as root certificates in all your clients. Did you really activate SSL/TSL on your NAS for local access? If so, unless everything is configured and set up correctly, both on the NAS and on the client, you will at best get error messages when you try to logo on, or at worst not be able to log on locally at all. And I trust you did not open your WAN-router/firewall port 443 and redirected it directly to your NAS servers for external access? If you did, that's asking for trouble.

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