Plex.tv says “The selected server cannot be reached securely. An insecure connection may be possible.”
However, an insecure connection is also not working.
On Android I can listen to my music just fine, and in Plex Media Player (OSX) it’s also working.
My server is running on Ubuntu linux, it always worked before.
Things I’ve tried:
I’m having a similar issues through multiple devices on the same network. Some can connect. Some can’t. This issue only started yesterday after working just fine for a long time.
To check if you have DNS Rebinding issues - get the xml returned by putting this request in a browser
https://plex.tv/pms/resources.xml?includeHttps=
Should sign in first to https://plex.tv before pasting that url into the browser
Then you will see connection uri’s for the server, a local one and a remote one.
Do nslookup on each to see if they translate ok and test them in a browser
eg
nslookup xx-xx-xx-xx.zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz.plex.direct
for each of the public ip and local ip uri’s
and to test in browser
for local ip one
https://xx-xx-xx-xx.zzzzzzzzzzzzzzzzzzzzz.plex.direct:32400/web
and for public ip - pick up the uri for that and put in the public port if different from 32400
When I do the first step, I get a list of devices and their connection info.
On the same PC, which is on of the machines that can’t see a shared user, I see the device of the remote computer. So this is the one I want to troubleshoot.
I’m not one to shy away from a command prompt, but I just want to make sure I follow you here. In the Command Prompt, I type in nslookup (what makes up the xx-xx-xx-xx and what makes up the zzzz’s? I tried the remote IP, for example, 68.123.456.789.plex.direct and it tells me my router can’t find, non-existent domain.
If you go to the first link he gave you it will display an xml file. The top lines are the different options for plex.tv to reach your server. Make sure they all work using nslookup.
Plex changed their certs or something in DNS.
Clear your cache on these devices, or try to use another DNS server as a test like 8.8.8.8 for Google DNS
I’ve ‘solved’ this problem…
Checking the ip-address directly gave me ‘401 unauthorized’. So the server is running.
NSLookup also seems to give me that answer. Tried in safari, chrome and vivaldi
I then switched networks: instead of wifi I went to my phone’s hotspot. Now it’s working.
Apparently it is some kind of DNS thing. I now have to wait until our provider (KPN) updates their DNS-cache.
Note: I can’t mark my own post as solving the question, because I edited it
@Dkrainbeau said:
I’m having a similar issues through multiple devices on the same network. Some can connect. Some can’t. This issue only started yesterday after working just fine for a long time.
@Dkrainbeau said:
When I do the first step, I get a list of devices and their connection info.On the same PC, which is on of the machines that can’t see a shared user, I see the device of the remote computer. So this is the one I want to troubleshoot.
I’m not one to shy away from a command prompt, but I just want to make sure I follow you here. In the Command Prompt, I type in nslookup (what makes up the xx-xx-xx-xx and what makes up the zzzz’s? I tried the remote IP, for example, 68.123.456.789.plex.direct and it tells me my router can’t find, non-existent domain.
I do not understand the bit about shared user
I thought we were troubleshooting your own server and using the main server master plex.tv account
Sorry I didn’t initially expand further, but it was one of the only posts that I saw that experienced a similar issue. I have my own plex server, but I have two other servers that are shared with me. Some devices in my house, on the same network, can access the shared server and some can’t. Just trying to troubleshoot.
for me it’s still not working on the remote wifi, by the way. So I’m highly doubting now that it’s a DNS thing.
So back to the start 
@GewoonM said:
for me it’s still not working on the remote wifi, by the way. So I’m highly doubting now that it’s a DNS thing.So back to the start
The easiest way to tell if it’s DNS is to test from a device that’s not working and change the DNS to pulbic DNS such as Google or OpenDNS. If it works after you change the DNS then that’s the issue.
If you scroll to the bottom paragraph on this link you will see that Plex states certain ISP’s who have DNS rebinding enabled will cause you issues. I believe Optimum is one ISP that has recently changed this and yours may be another one.
support.plex.tv/hc/en-us/articles/206225077-How-to-Use-Secure-Server-Connections
Oh, I’m a bit of an idiot
I changed the DNS-settings on the wifi-profile (on the Mac you enter it per connection type). Due to an unrelated issue, my internet dropped and I switched to cable. But I hadn’t changed the DNS settings on the cable-profile.
I’m now on the Google DNS for both and it’s working. Thanks IamSpartacus!
Following the DNS angle, I changed the DNS server on my router to OpenDNS and it seems to have resolved the issue.
