Lost access to NAS - possible DNS server problem?

[archivist]

Hi - so a few nights ago I abruptly lost access to my Qnap TS-453A NAS, and nothing I've tried yet has fixed the problem. I'm not all that much of a tech person (just setting up the NAS initially brought me pretty close to my capacity on that front), so I thought I'd bring the problem here and hope that someone more versed can tell me what I need to do.

The first thing I noticed was not being able to access my mapped network drives, but then I also found I could no longer access the NAS's settings through my browser. I can still see the device in Qfinder Pro (7.4.3), but on trying to click on it, it comes up:

"Cannot connect to device. Please check if the device and your computer are on the same subnet.
Click 'OK' to open the web browser and try to connect to device, or click 'Cancel' to return."

As far as I can tell, we do *appear* to be on the same Subnet Mask: the NAS's Subnet Mask is 255.255.255.0 (/24), and my PC's Wireless Lan adapter Subnet Mask (accessed via command prompt -> 'ipconfig/all') is also 255.255.255.0. I don't really know what I'm doing here though, or what a Subnet Mask even is, so I may be mistaken. One thing I can say is that it really doesn't seem like it's a problem specific to my PC, as I use the NAS primarily as media storage for an Android TV box, and that also stopped being able to see and access the NAS at the exact same time.

When I try to access the NAS's settings, the connection just times out ("The server at 192.168.1.123 is taking too long to respond.") When I try to do most other things in Qfinder (e.g. go into 'Network Drives', right-click 'Details', etc), it comes up with:

"Login failed. There was no response from the server."

So okay: to try and access the settings, I connected my computer directly to the NAS via ethernet cable. (The NAS's normal static IP had been 192.168.1.123; when connecting direct to my PC via cable, it was 169.254.9.27). This worked - I was able to access the NAS's settings through my browser that way - and the first thing that popped up was this error message:

"The system has detected that your DNS server cannot resolve hosts, and some applications might not work properly.
Please got to "Control Panel > Network > Network & Virtual Switch > Interfaces" and check if the DNS Server and default gateway is correct. You may contact your ISP for the DNS server information."

This was a lot more specific than the previous error messages I'd gotten, so I figured we were getting somewhere. I navigated to where it instructed me, and saw that the settings for my Adapter 1 (the one I connect the NAS to the router with) was set to "Obtain DNS server address automatically". I called my internet service provider, they provided me with the specific primary & secondary DNS address they use, and I plugged those in instead.

Unfortunately, that doesn't seem to have done anything to solve the problem, or even to resolve the error message. I still can't access my NAS through the network, and when I open up the NAS settings via direct ethernet connection, the same error message (about how "the system has detected that your DNA server cannot resolve hosts" and "contact your ISP for the DNS server information") still pops up. I'd thought that the DNS server thing must be the key to this, but now I'm not as sure.

Does anyone have any idea what I ought to try next? Because after that dead end, I'm a little stumped. I can see in Storage & Snapshots that all my data is safe, so I'm not overly panicked about that, but I really do need to get my NAS back up and running sooner or later. I'd appreciate any guidance anyone could give me, and you have blanket permission/invitation to speak to me like I'm a noob who doesn't know anything (because I am). Thanks!

Here's a big dump of additional info, in case any of it's helpful:

- My NAS's network details:

Fixed IP Address: 192.168.1.123
Subnet Mask: 255.255.255.0
Default Gateway: 192.168.1.1
Jumbo Frame: 1500
Network Speed: Auto-negotiation

- The system default gateway used to be on 'auto-select', but I tried changing it to Adapter 1 to see if that would change anything (it doesn't seem to have).

- My PC is running Windows 10, and when I do a 'ipconfig/all' in a command prompt, this is what comes up:

Windows IP Configuration

Host Name . . . . . . . . . . . . : <redacted>
Primary Dns Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Hybrid
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No

Unknown adapter Local Area Connection:

Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : ExpressVPN Wintun Driver
Physical Address. . . . . . . . . :
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes

Ethernet adapter Ethernet:

Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Intel(R) Ethernet Connection (2) I219-V
Physical Address. . . . . . . . . : 4C-CC-6A-F7-24-B6
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
Link-local IPv6 Address . . . . . : fe80::5d1c:5cca:5439:d492%4(Preferred)
Autoconfiguration IPv4 Address. . : 169.254.212.146(Preferred)
Subnet Mask . . . . . . . . . . . : 255.255.0.0
Default Gateway . . . . . . . . . :
DHCPv6 IAID . . . . . . . . . . . : 575458410
DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-21-FB-84-92-4C-CC-6A-F7-24-B6
DNS Servers . . . . . . . . . . . : fec0:0:0:ffff::1%1
fec0:0:0:ffff::2%1
fec0:0:0:ffff::3%1
NetBIOS over Tcpip. . . . . . . . : Enabled

Wireless LAN adapter Local Area Connection* 2:

Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Microsoft Wi-Fi Direct Virtual Adapter #3
Physical Address. . . . . . . . . : 00-28-F8-73-25-F9
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes

Wireless LAN adapter Local Area Connection* 13:

Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Microsoft Wi-Fi Direct Virtual Adapter #4
Physical Address. . . . . . . . . : 02-28-F8-73-25-F8
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes

Wireless LAN adapter Wi-Fi:

Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Intel(R) Dual Band Wireless-AC 8265
Physical Address. . . . . . . . . : 00-28-F8-73-25-F8
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
Link-local IPv6 Address . . . . . : fe80::fc6c2053:97dd%21(Preferred)
IPv4 Address. . . . . . . . . . . : 192.168.1.116(Preferred)
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Lease Obtained. . . . . . . . . . : Friday, 5 March 2021 1:06:12 PM
Lease Expires . . . . . . . . . . : Saturday, 6 March 2021 1:06:12 PM
Default Gateway . . . . . . . . . : 192.168.1.1
DHCP Server . . . . . . . . . . . : 192.168.1.1
DHCPv6 IAID . . . . . . . . . . . : 151005432
DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-21-FB-84-92-4C-CC-6A-F7-24-B6
DNS Servers . . . . . . . . . . . : 192.168.1.1
0.0.0.0
NetBIOS over Tcpip. . . . . . . . : Enabled

Ethernet adapter Bluetooth Network Connection:

Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Bluetooth Device (Personal Area Network)
Physical Address. . . . . . . . . : 00-28-F8-73-25-FC
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes

[Mousetick]

The DNS server error from the NAS is not the root cause, it's a symptom. Since you can connect to the NAS when wired directly to it from your PC, the most likely culprit is the router.

A few things you can check:
- The status of the network interface on the NAS (Network & Virtual Switches > Interfaces). It should say "Connected" in green and the Speed should be correct (1 Gbps), as shown in this example:

adapterstatus.png

- What does your router (which is also your wireless access point I guess) has to say about the NAS? Does the NAS show in the list of devices on the network, and if so, with what IP address?
- What is the DHCP address range on your router? Your NAS is configured with a static/fixed IP address which likely falls within that range. Normally this should not be a problem but your router may not like it for whatever reason.

A couple of things you can try, each separately, not together:
- Change the IP address of Adapter 1 on the NAS to something in the low digits, for example: 192.168.1.12. Click the little thingie on the right side (circled in green in previous screenshot), and select 'Configure' from the menu.
- Connect your PC to the router (not to the NAS) with an Ethernet cable. I doubt this will make any difference, but just in case.

Please indicate which firmware version your NAS is running (shown at top of main page in Control Panel).

[archivist]

Thanks very much for the reply! To answer your questions:

- The status of the network interface on the NAS does say 'Connected' in green, and the speed is 1gbps:

interfaces.JPG

(I can only access that page when the NAS is connected to my PC via ethernet though, which is in Adapter 3 and also 'Connected'.)

- The NAS is currently running firmware version 4.5.2.1566. Qfinder tells me there's a new version available, but when I try to download it from there, I get the same error message of, "Login failed. There was no response from the server."

- The NAS only shows up on the list of devices in the network when it's connected directly via ethernet to my PC. (When that's connected, the NAS shows up in the 'Computer' section of the Network page. From there I can go into it and access everything on the NAS.) When I remove the ethernet connection to the NAS though, it doesn't show up anywhere on the network.

- Re: the DHCP address range is on my router, I'd assume that it's the normal range of 192.168.1.2-254? Though I'm not totally sure how I'd find out for certain. Googling that question leads me to people talking about running scripts to perform 'DHCP exhaustion attacks', which seems way above my level of competence. That IP of 192.168.1.123 was the first one that the NAS was randomly assigned when I was setting it up, so I just kept it. (That was about a month ago, and it had been working fine up until a few days ago, for whatever that may tell you.)

So as you suggested, I changed the IP address of Adapter 1 to 192.168.1.12. Unfortunately, I still got all the same errors when trying to connect ("Cannot connect to device", "There was no response from the server", etc). So I then changed the IP address back to the old .123, and connected my PC to the router with an ethernet cable. (This is actually my usual setup -- I normally connect my PC to the router via ethernet rather than rely on the Wi-Fi.) So I've now got cabled internet back on my PC, but the NAS is still not showing up on the network.

As an additional 'may as well try it' test, I swapped out the ethernet cable connecting the NAS to the router for a different one. (It seems like the NAS's communication with the router is the problem here, so I wondered if it could be as simple as that.) That didn't make any difference though.

<redacted>

Any further ideas about what to try next? I really appreciate the help.

[Mousetick]

I'll respond later but for now please remove the information you posted about your router just above (starting at 'IP Address' and ending at 'Connection type'), for your privacy and the security of your network. Use the button with a pencil icon in the top right corner of your previous post to edit it. Bad people can use this information for nefarious purposes

[Mousetick]

- The NAS only shows up on the list of devices in the network when it's connected directly via ethernet to my PC. (When that's connected, the NAS shows up in the 'Computer' section of the Network page. From there I can go into it and access everything on the NAS.) When I remove the ethernet connection to the NAS though, it doesn't show up anywhere on the network.

- Re: the DHCP address range is on my router, I'd assume that it's the normal range of 192.168.1.2-254? Though I'm not totally sure how I'd find out for certain.

Usually the DHCP range on a home router is set to start at 100 (e.g. 192.168.1.100) extending upwards (e.g. up to 192.168.1.200 or 192.168.254), while the lower addresses (e.g. 192.168.1.2 to 192.168.1.99) are left for static/fixed assignments, but this configuration can vary depending on manufacturer or it can be changed by end-users.

To find out the DCHP range and whether the NAS is detected on the network by your router, you will need to login to the administration console of your router and look at its configuration and status pages. The same way you did to provide the information about your router in your previous post.

It's strange indeed that something broke down suddenly out of the blue. One hypothesis is that your router received a firmware update (e.g. my ISP triggers forced security updates remotely without me doing or knowing anything about them, or your router may be configured to automatically install updates by itself) which may have changed and broken something.

Other things you can try, again each separately:
- Change the configuration of Adapter 1 on the NAS from 'Use static IP address' to 'Obtain IP address settings automatically via DHCP'. Then note the new IP address that is automatically assigned and use it to connect from your PC to the NAS.
- Use a different Ethernet cable to connect the NAS to the router.
- Disconnect the Ethernet cable from the NAS and plug it into a different port on the back of the NAS (e.g. Adapter 2). Then note the new IP address that is automatically assigned and use it to connect from your PC to the NAS.
- Restart the router.
- Restart the NAS. In a controlled orderly manner, which means you'll need to connect your PC directly to the NAS via Ethernet cable and order a restart from the admin web UI or Qfinder Pro - don't simply power it down and back up with the power button!

Have you been using or merely enabled any kind of remote access feature on the NAS, such as myQNAPcloud?

[archivist]

Okay, so my problem appears to be solved! Though in a somewhat random and silly way.

I went through all the things you suggested trying, and nothing worked; I kept getting the "Cannot connect to device. Please check if the device and your computer are on the same subnet" message at every turn. I reset the router, reset the NAS via the web UI, discovered the DHCP range of my router (192.168.1.100-199), and tried all the different configurations you suggested and more. When I told it to obtain an IP address automatically, it would assign it an address that I could use to connect to it while it was connected via ethernet, but not through the network, and that was the pattern. No matter what way I tried to finegle it, I kept being told that I "cannot connect to device" through anything except the direct ethernet connection.

Then I tried the thing that worked, which was swapping the ports on the router that my PC and the NAS are plugged into. There doesn't appear to be anything at all wrong with the port that the NAS had been plugged into (it's giving my PC ethernet right now), and it had always said 'connected' in the NAS interface, so it was clearly plugged in correctly and reading it as a router ... but for some reason, putting it in a different port on the router made it work *immediately*. It assigned the NAS a new random IP address (192.168.1.105), through which I was able to access it via the network, with no direct ethernet connection. Then I was able to finally download that firmware update for the NAS, change the IP address back to 192.168.1.123, and all my old mapped network drives and everything are working again.

(Perhaps I shouldn't have changed it back, given the trouble, but I figure since the new one it was assigned was in the same number range, and changing it back to .123 is significantly easier with my whole media library setup, I may as well.)

I truly have no idea why this worked. It's possible that the changing of the router ports didn't actually do anything, and something else somehow changed at the same time ... but I genuinely was doing everything one step at a time, always checking back as I went, so it's hard for me to see what else could have changed. It wasn't allowing connection to the NAS through the network, at all, for days and days, and then I switched the ports that the PC's ethernet cable and the NAS's ethernet cable were going into, and suddenly it was.

Thanks very much for your help. I'm extremely perplexed by what the solution turned out to be, but I'm not looking a gift-horse in the mouth.

[franksch]

Dear archivist,
I had the same/similar problem; no access, but also no access anymore via ssh. The helpdesk advised to reset the nas by sticking a paperclip in the little hole at the back. This resets the admin password to the standard. (The MAC address I believe) This solved the problem for me.
It doesn’t explain why happened though...
Regards,
Frank

[PSetiawan]

This is a legitimate bug and QNAP support confirmed they are not gonna fix it.
I repeat they are NOT gonna fix it.

Any qapps require their own network like the notorious container station will add IPs to the NAS dns which mostly a local ips.
Connection is lost when those ip became default through nslookup round robin.
A workaround is deleting all those unwanted ips.
But they ALWAYS come back when you do any of these :
1. restart the NAS
2. restart the bugged apps (like container station)

Since QNAP has given up you best be vigilant.
I have phased all QNAP products to non essentials in my environtment.

[Twinastir]

I had similar problem after the upgrade to QTS 5.x. I was obliged to a firmware downgrade (last 4.x) to solve the issue.