Plex Media Server cannot be claimed - logs say "Could not resolve host: plex.tv"

Plex Media Server NAS & Devices
1

Server Version#: 1.29.2.6364-7000
DSM Version#: 7.2.1-69057 Update 3
Plex Media Server (1).log (862.6 KB)

Hi,

I’ve been running a Plex server for the past 2 weeks and with the exception of the occasional metadata not displaying, I’ve had no issues with it. Today, suddenly, I was unable to access the server anymore.

I logged in to it just fine at about 9AM and then at around 10-ish when logging into the web portal, it kept saying that the server is unavailable.

I am running the server on a Synology DS923+ and I have initially updated the server to v1.32.

Nevertheless, since this morning I’ve installed and uninstalled the server more times than I can count, trying to fix this access problem.

At one point I got it showing the server itself, however, as it appears in the screenshot below, I can’t claim it. I click on the button and nothing happens.

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The logs show at one point the error “Could not resolve host: plex.tv”, however, the website is accessible from all devices in the house. I even reset the router thinking it’s a DNS issue. It can’t be because port forwarding is activated on the router, the NAS has a static IP, port 32400 is set under port forwarding on the router… I honestly don’t know what else to try/do.

Can anyone help?

2

This is a DNS issue.

One thing you probably overlooked is the DS923+ itself.
It must also be configured to use your router’s DNS and as a Gateway to get to Plex.tv

Go to: Control Panel - Network - Edit the appropriate interface you’re using.

If you’re using multiple adapters, Start with eth0 as this is the DS923+'s default and what PMS will use when multiple are connected. Also make certain to check the appropriate “Use as default gateway” checkbox.

We know it worked at one point but something must have changed in the Syno’s network configuration

3

Thank you for the reply!

I just checked the settings and no dice. Same thing happens when setting the default gateway :frowning:

image

Note: The manual configuration works for everything. All other services running: Radarr, Sonarr etc. are working without any issues with the current settings.

Only Plex has this issue and there have been no changes to the DSM version or other settings between the last time the server worked and when it stopped working :frowning:

It’s also worth mentioning that I am using Reverse Proxy for every service running, using the *.name.synology DNS since first getting the NAS set up and have disabled Quickconnect a few days back, if that matters.

4

As I was writing, you posted this.

Proxies are a PITA. They interfere with the certificate & SSL.

Synology QuickConnect will prevent you from claiming it
(because there is a FQDN in the URL).

Given this appears to be a DNS issue, May I see a manually captured ZIP of the logs?

(PlexMediaServer/AppData/Plex Media Server → Right-click Logs → Compress to Logs.zip)

5

Here it is:

Logs.zip (175.7 KB)

But I have to ask: how can the quickconnect feature, which I disable a few days ago, interfere with the install today? I mean, why would the server even look at the quickconnect DNS?

6

Thanks for the logs.

It’s very clear that something is blocking the lookup of both v4.plex.tv and plex.tv
(which are hosted on Amazon AWS)

The forum is hosted on discourse (obviously not blocked)

[chuck@lizum ~.2006]$ nslookup v4.plex.tv
Server:		127.0.0.53
Address:	127.0.0.53#53

Non-authoritative answer:
v4.plex.tv	canonical name = a77dd7564d57b4db9a446af0f8b74064-321560369.eu-west-1.elb.amazonaws.com.
Name:	a77dd7564d57b4db9a446af0f8b74064-321560369.eu-west-1.elb.amazonaws.com
Address: 52.214.102.6
Name:	a77dd7564d57b4db9a446af0f8b74064-321560369.eu-west-1.elb.amazonaws.com
Address: 52.31.155.243

[chuck@lizum ~.2007]$ nslookup forums.plex.tv
Server:		127.0.0.53
Address:	127.0.0.53#53

Non-authoritative answer:
forums.plex.tv	canonical name = plex.hosted-by-discourse.com.
Name:	plex.hosted-by-discourse.com
Address: 184.105.99.43
Name:	plex.hosted-by-discourse.com
Address: 2602:fd3f:3:ff01::2b

[chuck@lizum ~.2008]$

Do you have access to a Linux/Unix command line or sufficient tools to do the equivalent of this?

[chuck@lizum ~.2008]$ curl http://52.214.102.6
Moved Permanently[chuck@lizum ~.2009]$ curl http://v4.plex.tv
Moved Permanently[chuck@lizum ~.2010]$
7

Does curl need to run on the NAS?

If not, Windows 10/11 has curl: curl shipped by Microsoft.

c:\>curl http://52.214.102.6
Moved Permanently
c:\>curl http://v4.plex.tv
Moved Permanently
c:\>
8

It doesn’t need to run on the NAS to confirm DNS lookup works.

9

I ran the 2 commands on both my PC and the NAS.

In both cases, the “Moved Permanently” status appears.

10

If both are working from the NAS SSH command line then WTH???

There is no reason 1.29.2.6364 should fail.

Just in case, here is 1.32.7 for your Syno.

Please perform a Manual Installation

After this, restart DSM

11

Updating worked, the server could be claimed, but now I’m having this issue:

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The server appears as not available outside of the network and when attempting to login to it through app.plex.tv, it shows “app.plex.tv is unable to connect to “server” securely” + :

image

12

Please grab your server logs again for me?

When it can’t get its own Public IP , there is still a problem talking to Plex.tv

Normally, at this point, UPNP (in the modem/router) will open the ports for Plex.tv
Additionally, if your Synology firewall is active, we’ll need to make adjustments there too.

13

Ports were opened on the router by me and I deactivated the Synology firewall when this whole thing started.

Here are the logs.
Logs.zip (2.6 MB)

14

Thank you … This is what I needed to see.

Jan 08, 2024 21:22:10.031 [140454217358136] DEBUG - NAT: UPnP, not an IGD: <http://192.168.1.1:5000/Public_UPNP_gatedesc.xml>.
Jan 08, 2024 21:22:10.031 [140454217358136] DEBUG - NAT: UPnP, didn't find usable IGD.
Jan 08, 2024 21:22:10.031 [140454217358136] DEBUG - NAT: PMP, attempting mapping.
Jan 08, 2024 21:22:10.034 [140454163172152] DEBUG - Request: [127.0.0.1:47824 (Loopback)] GET /servers (5 live) #12 GZIP Token ()
Jan 08, 2024 21:22:10.035 [140454234544952] DEBUG - Completed: [127.0.0.1:47824] 200 GET /servers (5 live) #12 GZIP 0ms 487 bytes
Jan 08, 2024 21:22:10.037 [140454215248696] WARN - [HttpClient/HCl#3] HTTP error requesting GET https://v4.plex.tv/pms/:/ip (6, Couldn't resolve host name) (Could not resolve host: v4.plex.tv)
Jan 08, 2024 21:22:10.037 [140454202141496] ERROR - PublicAddressManager: Unable to get public IP adddress from myPlex (httpCode=-6):
  1. PMS sees the modem/router at 192.168.1.1 (where DSM points)
  2. Asks, using UPNP, if it’s a gateway (modem/router) device
  3. UPNP responds with NO.
    – Is UPNP disabled on the modem/router ?
  4. PMS then blindly sends out the GET https://v4.plex.tv request to DSM.
    – DSM can’t get the address so replies back with DNS error 6

Is there anything else between the Syno → Modem/router → Internet ??
Any kind of filter/router hardware or software ?
Is a VPN involved ?

15

Nope, no VPN involved and there’s nothing inbetween the NAS > Router > Internet. Everything is connected via LAN, the NAS goes through a switch (unmanaged) and then straight to the router, no extras. And the router, under UPnP, shows all the ports being used by Plex, so it goes through UPnP.

16

So, I managed to get the server to say that it’s accessible outside the network by setting a manual public port and then removing it.

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But it still doesn’t show Private IP > Public IP…

17

The Public IP won’t work if DNS to http://v4.plex.tv fails.

This is what’s holding you back. — DNS lookup is failing.

Where is your modem / router pointing to for DNS resolution?
Is it pointing to the ISP or to google ? (8.8.8.8 / 8.8.4.4)
– You can also try this in the Syno manually if you wish

18

It’s pointing to the ISP DNS, not a custom one.

I haven’t changed this at all for at least a few years. And it’s less likely for the ISP to have changed something because I have their router set as bridge and am currently using my router to connect to the ISP

19

Would you be willing to try it in the Syno only?

I know your other things work but given how weird this problem is,
and that nobody else is reporting it,

I’m running out of ideas.

The only way I know to be more definitive is for DSM itself to make the query to google.

This is what I’m suggesting changing – just to test.
You can change it back if no improvement after restarting Plex

Screenshot from 2024-01-08 17-38-54

20

Setting the Google DNS on the syno fixed it. But what is the underlying issue? Is my router slowly kicking the bucket? Or is my ISP somehow messing with their DNS servers? Is this second possibility something that you’ve heard of before?

Because this is the first time something like this happened and to be honest, the first part of the issue with the server not being claimable still doesn’t have a definitive resolution, because it worked after the upgrade but we don’t know why…

And this second thing… I mean, I haven’t changed anything in my home network since adding the extra switch, which is unmanaged, so it shouldn’t matter…