Hezron Munge Chacha

CCNA (R&S), MCP (Windows Server 2012), Google Adwords Certified, SEO Specialist, BSc. Computer Science.

[Solved] Error when connecting to GNS3 server: Cannot connect to

By Hezron Chacha | October 30, 2017 | 2 Comment


I downloaded GNS3 and successfully installed the latest version (2.0.3) on my laptop that is running on Windows 7 Professional Service Pack 1 (64 bit). I got an error while trying to connect to the server “Error when connecting to the GNS3 server: Cannot connect to Please check if GNS# is allowed in your antivirus and firewall. And that server version is 2.0.3.”



How to fix the error:

I tried to google a number of blogs to help me fix the error and finally got the fix. From my research, it appeared that this error happens when you first run GNS network simulator on a Windows as well as Linux operating system environment.

The simple fix before you check your anti-virus (McAfee as for my case) and firewall software, run GNS3 as an administrator and it works perfectly.



This fix works well to resolve the error “could not connect to on port 800: [WinError 10061]No connection could be made  because the target machine actively refused it.” This error occurs when you drag and drop some devices like router on the GNS3 network simulator. Read More on this article.



Photo credit: Technig


22 October, 2018 Reply

I ran it as administrator but that did not make the trick, i am still seeing that nasty error -could not connect because of firewall-

    Hezron Chacha

    03 November, 2018 Reply

    Have you disabled the windows firewall?

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