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I have been attempting to open a port to host an Arma 3 server but have been unable to. I have a logged into my router, and opened the ports, but they remain closed when I try to test the ports.

I have a rather unusual setup for my connection, I'll admit, where I use Ethernet, but its through a Powerline Ethernet Adapter. Could that be a problem with port forwarding?

I use an older router, a Motorola MT7700, I think, (Im not at home to check atm.) I run Linux Mint, it has no problems afaik.

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[-] BootLoop@sh.itjust.works 2 points 1 month ago

Perhaps your ISP doesn't support port forwarding? I could never get port forwarding to work on the crappy rural internet providers I used to be on.

[-] slazer2au@lemmy.world 1 points 1 month ago

Do you actually have a public IP on your router?

Some carriers will give you a private that is the CGNATed those addresses are 100.64.0. to 100.127.255.255

[-] trslim@pawb.social 1 points 1 month ago

I have checked this, and yes I do have a public IP.

[-] Zachariah@lemmy.world 1 points 1 month ago
[-] trslim@pawb.social 1 points 1 month ago

ok, so it is saying it cannot see me through that port

[-] mvirts@lemmy.world 1 points 1 month ago

When you say open a port you mean forwarding connections to that port to your machine inside your lan?

Next steps I would take are to verify you can access the port within your lan

I.e. if your machine has a local IP of 192.168.1.23 and your service is listening on port 4200 try connecting to 192.168.1.23:4200 from another device on the lan, or even from the machine itself although I'm not sure that's always a good test.

You can also try nmap to scan you lan or netstat on the host to check what ports are in use.

If that fails you may have a restrictive firewall on your machine blocking inbound connections. A quick check to see if this is the problem is to disable the firewall entirely, just remember to turn it back on if you need it!

If you can access it locally on the lan, sniffing traffic with Wireshark may help debug the issue. You should be able to see the router sending forwarded traffic into the lan. If the configured IP address is not known to the router you may just see arp requests for who has [IP address to forward to]

but they remain closed when I try to test the ports.

Have you had someone else try? Not all routers correctly handle NAT reflection. Try a too like this.

https://www.yougetsignal.com/tools/open-ports/

this post was submitted on 03 Oct 2025
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