Getting error "A connection could not be established. Reason unknown"

Vishal
Vishal Posts: 1

Hello Evenryone, 

I am using Teamviewer 12 on Ubuntu 16.04 , while connecting to some of the host machines running same version of Teamviewer , I get "A connection could not be established. Reason unknown" error. 

This is shown even after many a attempts and when both the machines i.e. host machine and mine have been restarted. 

Please note that I am able to connect to other machines running Teamview 12! 

Looking forward to a solution. 

Thanks in advance 

Regards  

Vishal 

Comments

  • ChristianCay
    ChristianCay Posts: 182 [Former Staff]

    Dear Vishal,

    Thank you for your post.

    This message might be shown because of many reasons.

    For example, connection issues, the computer is not responding, etc.

    Have a try by disabling UDP when you have this issues.

    Could you please test whether deactivating UDP (Extras->Options->Advanced->Show Advanced Options->Advanced Network Settings->uncheck "Use UDP (recommended)") solves the problem?

    For performance reasons, please remember to reactivate this option if the problem can not be solved this way.

    Thank you very much in advance.

     

    Best Regards,

    Christian

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  • walldoo99
    walldoo99 Posts: 5 ✭✭

    I think a lot more people are having this issue and can't find this post

  • I am seeing this error for the first time, after upgrading my personal computers to Version 13.  I couldn't find a solution nor troubleshooting steps. Even after reinstalling the software (same version) on both computers, the problem remained the same.  

    A solution or troubleshooting steps would be much appreciated.  - MG

  • ChristianCay
    ChristianCay Posts: 182 [Former Staff]

    Dear MGogulapati,

    Have you tried disabling UDP?

    Another solution is force TeamViewer to work on outgoing port 80.

    On Linux, open your choice of a file editor and add the following line in the global.conf file that can be located here: /opt/teamviewer/config/global.conf

    First, stop the daemon with the command

    sudo teamviewer daemon stop

    Then add the following:

    [int32] AllowedConnectionProtocols = 3

    After this, please restart the TeamViewer daemon

    sudo teamviewer daemon start

    In Windows, do the following, please open the regedit on the machine, and navigate to the path below:

    32 bit: HKEY_LOCAL_MACHINE\SOFTWARE\TeamViewer
    64 bit: HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\TeamViewer\

    Create a new DWORD 32 registry key, and name it AllowedConnectionProtocols with the decimal value of 3 and restart the device.

    Thank you in advance and I look forward to hearing from you.

    Did my reply answer your question? Accept it as a solution to help others, Thanks.
  • walldoo99
    walldoo99 Posts: 5 ✭✭

    why would we have to edit the register in windows? I can understand having to just through hoops in some linus distros, but not windows or apple.

    I find it interesting that this problem is so wide spread, but if I run my VPN, no problems connecting. hmmm

  • I am getting the same error on upgrading to version 13

  • Sorry, I couldn't help with changing registry settings on Version 13.   

    I have downgraded teavmviewer to Version 12 all my computers, and the problem was resolved.   I had to restart computers couple of times though. 

    I am sure, the connectivity issues are related to new secuirty settings in Version 13.  I will wait for more stable version. 

    MG 

  • htennek2k
    htennek2k Posts: 1

    Hello folks.

    I usually use TeamViewer as a PhD Student to connect from my lab computer (iMac) to my home computer (Windows 8 Laptop). Had this problem this morning. 

    I got it solver by upgrading TeamViewer in both machines. I'm lucky my wife was home.

    So, hopefully this will be the case for all people having this issue.

    Good luck!

  • I am glad it is working for you on Windows 8.   

    Teamviewer 13+ connectivity is intermittent to/from Windows 10 with IP-V6 computer. 

    All my computers are on Windows 10 with IP-V6 enabled.   As of now, the only workaround for making the teamviewer (version 13+) connectivty work is to "Disable IP-V6 either on source or destination computer" .    I am not sure, when teamviewer is considering to support IP-V6.   

    MG

  • This worked for me. I was having the issue between two Ubuntu machines.

    However, stopping and restarting the daemon was all that was needed. The config option wasn't necessary.

     

  • I am having this error when trying to access my computer through my ipad. I disabled the UPD. It didn't work. Not sure about what else to try.

  • This seems too advanced - Im looking for solution of this problem while connecting from Ipad

  • emma_luk1
    emma_luk1 Posts: 1

     

    same to me