If you don't know what Port Forwarding is yet, you might want to start by reading our What is Port Forwarding guide.
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The 3c510 will not allow you to forward enough ports, to run Throne of Darkness. You should try using the DMZ portion of this router if it is available. Alternatively you can try switching the router to bridged mode. You will need to contact your ISP to switch to bridged mode, so they can make the required changed on their end.