"SocketException: System call failed" from "ExitGames.Client.Photon.SocketUdp.DnsAndConnect"

Hi all,

My team has received some reports of user's who are failing to establish a connection to the game with this being written in the logs.

The user's are failing consistently after multiple attempts.

The server's they are connecting to are servicing other user's, so I don't think it's an issue with our server configuration.

Here's the stack trace written in their output log

Connect() to '{one of our servers}' failed: System.Net.Sockets.SocketException: System call failed
at System.Net.Sockets.Socket.Connect (System.Net.EndPoint remoteEP, Boolean requireSocketPolicy) [0x00000] in :0
at System.Net.Sockets.Socket.Connect (System.Net.EndPoint remoteEP) [0x00000] in :0
at System.Net.Sockets.Socket.Connect (System.Net.IPAddress address, Int32 port) [0x00000] in :0
at ExitGames.Client.Photon.SocketUdp.DnsAndConnect () [0x00000] in :0

The one thing the user's seem to have in common is that they are using Mac desktop, but we don't know which versions of the OS specifically (we're working on getting that info).

Is there any known causes for this issue from a Photon perspective?


  • We've tried 2 things so far as troubleshooting goes.
    1) instructed the user to reset their location under System Preferences > Network
    2) reset their configuration under /Library/Preference/SystemConfiguration

    Neither resolved the issue.
  • hi, @aowen

    are mac desktops under windows?
    What client lib are you using?

  • Hi @chvetsov !

    These are consumer Mac desktops, I don't have reason to believe they are doing any sort of virtualization over Windows.

    We ship with Photon3DotNet.dll, v4.0.5.0.

  • hi, @aowen
    So, this is mac desk under OsX. you are using Runtime client sdk.
    and they are not able to connect?

    everything is right?

    Do they have Firewall on the machine?
    Are corresponding ports are open in their LAN?

  • Hi @chvetsov

    We sent out a request for them to add our application under their list of accepted programs in their Firewall, so we're waiting to hear back on that. We tested this case ourselves though, the case where traffic is being blocked, and we didn't replicate the "system call failed" error.

    Their LAN would be the next place for us to investigate, although we can't count on the user being tech savvy, so we have to write some simple instructions to test if the issue lies with their environment.

    My fingers were crossed that this was a known issue, perhaps with a known solution, but that may not be the case.
  • TobiasTobias admin
    Version is really old (3. December 2015). You should update.

    If the IP of your server is correct, then this is likely a problem where the traffic is blocked or the IP is not reachable. Otherwise the connect should work.
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