Previous remote user can no longer connect

Plex Media Server
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Server Version#: 1.24.3.5033
Player Version#: 4.66.1

I have a friend to who I have been successfully serving content for a while. Recently she had been having problems with her internet and eventually switched ISPs. She has the same ISP as I do now (Cox) and things are better but she still isn’t able to connect to Plex. She keeps getting that the server is not available and I think sometimes she gets that she can’t connect securely, even though I’ve allowed insecure connections. This even after deleting and re-inviting her several times.

Note I have several other friends that successfully use my server with no problems.

The other day I was at her house and decided to try a few things. First I connected to her WiFi and attempted to run Plex on my phone as her user. We had some difficulties with signing in (turns out she was using the wrong password). We switched to her laptop and tried signing into the Plex web app. After that, all we would see is that the server is not available. I then logged in as my account on my cell phone and tried to delete and re-invite her. Funny but the Plex app on the phone doesn’t allow you to do that. So I fired up a browser and went into app.plex.com. I tried deleting her user but it wouldn’t work. I tried tapping the little “X” by the user, even zoomed in a lot so my fat fingers would hit the right spot but each time I did that it just went into Edit User mode. Frustrated I went to her laptop, signed her out of Plex, and signed in as myself. I was able to delete and re-invite her but to my surprise, I couldn’t even see my server from the Plex web app on her laptop signed in as myself. I could see my pinned items and I could even see my friend’s Plex server that I had subscribed to long ago that got me into Plex and eventually got me to run my old server. But even his server was unavailable!

All this makes me think there are gremlins still in her network and with her ISP. I don’t think Cox blocks any ports that would affect Plex (I know they block ports like 25, etc. but not 32400). Why would this user, who used to use my service, be getting these errors? Not sure she’s running a firewall but I asked her.

Perhaps the new Cox router has a firewall on by default? By default Cox says their “typical” firewall settings block:

LAN-to-WAN: Allow all.

WAN-to-LAN: Block as per below and enable IDS.

IDENT (port 113)

ICMP request

Peer-to-peer apps:

kazaa - (TCP/UDP port 1214)

bittorrent - (TCP port 6881-6999)

gnutella- (TCP/UDP port 6346)

vuze - (TCP port 49152-65534)

Those don’t seem to be Plex ports…

What troubleshooting tips can I use to debug and fix this. I’ll have to do them myself as this user shy’s away from any remote debugging.

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My friend said that she had tried lowering the firewall’s level to low and that didn’t work.

Does anybody have any tips how I can debug and fix this?

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Let’s be careful w/ tinkering around with the firewalls.
Let’s start with the basics… are you able to access your Plex Media Server from outside your home network?

How have you configured the remote access? This is not so much about your router’s firewall but the port forwarding. If your router supports it, try using a manual port forward. Make sure the remote access of your server is enabled and configured according to your router’s port forward configuration.

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Yes, I can access my Plex server from my cell phone on cellular data as well as things like public WiFis. I have many remote users. They are able to access my server from their homes. This one user cannot. Yes, I have configured the port forwarding correctly as other remote users can use it. Again, just this one remote user cannot re-establish contact with my server. I also use Tautulli, NZB360, and other apps to monitor my server remotely from my phone. This all works. For me. But not for this one user so I’m trying to troubleshoot her connection through her home network and through her ISP (which is the same ISP as me - Cox).

I should be able to telnet from my phone to <my router IP>:32400 while on her home network wifi right? I want to try that next since I have an app on my Android phone that supports telnet. Correct me if I’m wrong but if I can telnet into my server at port 32400 then Plex should work. And if I can’t then somebody or something is blocking that port, correct? Or am I off base here.

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Thanks.
If it’s working for you and other users, then your remote access configuration should indeed not be the issue.

Pinging your router’s public IP / the port used for your port forward (as an alternative to using telnet)

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If I cannot telnet to my public IP and 32400 then what is the next step in debugging this?

I did the following to test.

  • Configured the ConnectBot app on my phone to have a connection to my router’s public IP address at port 32400.
  • I’m able to connect both from my home wifi and from just on cellular. Since I don’t know how to talk to the Plex server and it didn’t announce itself I assume that the fact that it didn’t complain indicates I successfully connected to my home Plex server on that port.
  • As a test I change the port to 32401, a port I’m not using and haven’t forwarded. This time ConnectBot reported Connecting to my router’s public IP:32401 via telnet and went no further. I take this to mean it is unable to connect. This was on my home network. If I switch to using cellular I get an immediate “Connection Lost”.

Assuming that I will not be able to connect to my Plex server when I’m at her house what would be the next debugging step to take?

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Contacting her ISP?

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So I call up Cox and say “Hey man, why aren’t allowing some customers from connecting to my illegal Plex server so they can watch stuff from me instead of paying those big companies bottom lines”?

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No… open powershell

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image1578×777 56 KB

replace ip with your external ip address, and port with the port you designated.

Test-NetConnection 0.0.0.0 -port 32400

run this multiple times if you’re curious but likely testsucceeded will come back false. if so then it’s her firewall. if not, then running the command multiple times will show flakey connection.

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Your friend, using the same ISP - is she geographically close to you?

On some cable ISP systems it’s not possible to communicate between two subscribers that are on the same infrastructure “node”.

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She’s about ~18 miles. I fail to see any reason why two computers on the same ISP’s infrastructure node would have any problems communicating with each other.

I guess another interesting test would be to see if she can go to any of my home domains like sonarr, tautulli, etc. that I have set up and run on my Synology at home.

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Modern cable modems don’t communicate directly with each other, only with the head end.

Sometimes the routing is configured to allow local stations to communicate, sometimes it isn’t.

DOCSIS - Wikipedia #Security

The tests you’ve described are the easiest way to confirm. If your IP addresses are adjacent, if you can’t ping or reach any services between them, that may be the cause.

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If this is indeed the case, what can be done? I mean I don’t think I could call up Cox and say “Hey, I want to share my Plex server with my friend and you’re blocking it”. Are there any other workarounds I could use?

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That might work just fine. Or “I’m trying to play a game with my friend” or “I’m trying to share my screen with my friend”.

But one step at a time. Confirm the behavior before making more plans.

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That would require that I run Windows. I don’t. I run Ubuntu and my friend is an iPerson…

Perhaps you meant telnet(1)?

Actually, since I wasn’t about to lug a laptop over to test there I set up a connection using ConnectBot on my Android phone. However, my friend informed me that suddenly everything was working. That’s the thing with this friend, I get no explanation to sudden “Gee it’s working now” nor am I allowed really to do any forensic work.

ALso, I think you meant -tcpport, at least that’s what the MS docs for Test-Connection seems to indicate.

1 Like
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Well at least it’s working for her. I suspect the issue will reappear at some point but hopefully not :slight_smile:

Test-NetConnection is the successor to test-connection, which you googled, and has the -port trigger. Also you could install powershell if you were truly were bored enough to do so (lol); I was just doing this the other day to fool around with a github onedrive project for this crossover application we’re developing for this group that’s heavily teams oriented and relies almost entirely on sharepoint. (but i digress)

For ubuntu telnet would work fine though it’s being phased out. Suggest using nmap or ncat, especially in scripts. Best of luck to you.

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I’m not that bored and I really don’t want MS crap infecting my Linux system. Telnet will never die!

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