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In Game Host feature doesn't work in both main and experimental
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I am currently experiencing difficulties with hosting a server in-game. When players attempt to join, they encounter a black screen displaying a loading icon, and they are subsequently disconnected due to a replication error.

Troubleshooting steps i have tried:

Used my IP4 address
Left the Ip empty
Tried my public IP address.
Restarted my modem and router.
Tested on a different network.
Allowed necessary ports through my firewall.
Forwarded necessary ports on my router.
Additional Information:

I have attempted hosting the server on two different computers within my household. One computer successfully connects to the server using my IP4 address, but it experiences high ping. However, when using my public IP address, the other computer fails to join the server and encounters the same error as external players. To further troubleshoot, I even tested the server on a cellular network, but the replication error persisted.

Back, in December, players were able to join my server, albeit with a high ping. However, currently, server hosting only functions within the local network and does not work at all for external players.

I have my logs and another's logs from the experimental branch


Operating System
Windows 11 x64
Steps To Reproduce

Host a ingame server and have players join from outside your network it should fail.

Additional Information

Event Timeline

g1972 created this task.Thu, May 11, 3:58 AM
Geez changed the task status from New to Awaiting internal Testing.Fri, May 12, 2:19 PM
Geez added a subscriber: Geez.Tue, May 16, 4:10 PM

Hello g1972.
We will need the following:

  1. the server config you have used, you can save it by doing following:
    from there you can name the config as you want to
    and after confirming, the server config .json file will be saved in your profile folder

C:\Users[yourusername]\Documents\My Games\ArmaReforger\serverConfigs

  1. Second thing we will need is for you to try hosting a dedicated server so we can see if the issue comes from the fact that you are running a Listen Server or if the issue is coming from an external factor, such as your network or setup. If it's complicated one of the devs can be put into contact with you
g1972 added a comment.Tue, May 16, 7:44 PM

This one is using my ip4 address which allows my other local machine to connect but not others from out of network and this one has the 999 ping. This one uses my public ip and it shows good ping for everyone but no one cant join it. Ill post the dedicated server stuff soon i have to get it setup

g1972 added a comment.Wed, May 17, 2:41 AM

So i tried the dedicated server. And only my local machines could join when i left the bind ip blank. When i changed it to my public IP once again no one could join. So for me both the listen and dedicated server is not working. I don't know if this is relevant but with the person i was testing with we can host and join our arma 3 games just fine so i assume its not anything to do with our network situation. The problem is exclusive to reforger. Let me know if i can provide anything else thank you!

Hi, g1972,

there are a few things that can go wrong and without knowing more about your home network topology, as well as how has your ISP set things up for you on their side, I can only make recommendations based on what we have seen players struggle with the most.

First off, Usingip4.json config is only going to work for other players on your home network (in the same subnet as server). I am almost certain that 999 ping is just a consequence of server being unreachable from external networks. publicip.json config is set up correctly (assuming gameHostRegisterBindAddress in it is correct). However, on its own, it might not be enough to make things work. gameHostBindAddress should be left empty or Other values would restrict who can connect to the server even further, but when troubleshooting connection issues, we don't want to do that.

Next I would verify that public IP you have in publicip.json config set as gameHostRegisterBindAddress is correct and up-to-date. It is possible (even if unlikely) that it has changed, so best to check what public IP address you have using one of the free services on the internet, such as .

At this point, everything in config should be correct. Here is a list of the most common things preventing connections that people may encounter:

  1. Port forwarding is not set up correctly. If there is protocol specification next to port, it should be UDP (other option is TCP). If there is room for two port numbers (eg. source port and IP+port being mapped to), both should be 2001 based on your publicip.json config.
  2. Your public IP address is not address of your home router. This may be the case when your ISP has put you (along with other households) into a subnet within their infrastructure. Unfortunately, the only thing you can do in this case is contact your ISP and request public IP address that would be statically assigned to you. ISPs may (and often do) charge extra for this.
  3. Your router is not forwarding packets from private subnet targeting its public address through port-forwarding rules into private subnet. This is usually referred to as NAT hairpinning, reflection or loopback (wikipedia section describing the concept). While this shouldn't get in the way for players outside of your home network, it has to be enabled for client and server on same subnet to connect when using public IP as gameHostRegisterBindAddress. Some home routers may not support this at all.

Since you were able to connect machines on same subnet using local address of your server (the one in Usingip4.json), this suggests to me that at least some of the points above are affecting you. Usingip4.json config basically makes the server only reachable from same subnet by connecting directly. Since it also rules out all NAT, port forwarding and hairpinning issues you might be facing, the fact that you were able to connect from client on same subnet using this config means that server itself is configured correctly and issue is somewhere in routing through public IP and port.

g1972 added a comment.Wed, May 24, 8:38 PM

As it turns out i just needed to port forward it works now thank you!

Geez closed this task as Resolved.Thu, May 25, 11:05 AM
Geez claimed this task.