Cannot connect to CS:GO server from outside home network.

[Kiwilover112]

I have recently set up a CS:GO server on my PC for my friends and I to play on. I have successfully set it up and can connect to it via LAN. I have also port forwarded the 27015 and 27016 in my router settings to allow my friends abroad to connect to it. When they try and connect they are taking to the loading screen in CS and are then taken straight back to the menu with no error messages. In console, the only error is:

 ChangeGameUIState: CSGO_GAME_UI_STATE_LOADINGSCREEN -> CSGO_GAME_UI_STATE_INGAME
 Unable to localize '#GenericConfirmText_Label' on panel descendant of 'MMStatus'
ChangeGameUIState: CSGO_GAME_UI_STATE_INGAME -> CSGO_GAME_UI_STATE_MAINMENU
PNG load error Interlace handling should be turned on when using png_read_image 

I can tell they are connecting as in my router logs I can see

 [LAN access from remote] from <Friend's IP> to 192.168.1.117:27016, Friday, February 05, 2021 11:42:01 

I have also tried using another PC in my home network and connected via the external IP, as my friends tried. When trying this the PC is able to connect, leading to my suspicion that there is some firewalling issues with my router. I tried setting my PC up as a DMZ to remedy this but to no avail. Any help would be appreciated.

[Blaquicat]

You have to make sure you aren't under any GCNAT.
Type status on console and check your public ip.

[Kiwilover112]

I have done this and all my IPs match up, including that on https://www.whatismyip.com, I think this shows I am not under a GCNAT, any other advice?

[[N]ebsun]

firewall on the host computer, or lan only setting on the game server, or ip binding issue on the host computer (try -ip 0.0.0.0 so it binds to all interfaces)

[Kiwilover112]

Thanks for your reply, I've just tried your suggestions but it didn't seem to help much, any other steps I can take to potentially debug the issue?

[[N]ebsun]

udp port forward?

[Kiwilover112]

I've forwarded the ports using TCP/UDP so I think that covers it. Images attached: https://ibb.co/G320rrZ https://ibb.co/mcyZ5Dz

[Blaquicat]

Check the wan ip address on the device, it could be another "internal ip".
Disable windows firewall

[FirePowered]

Good

[Salvador]

Nice

[Aim]

We had a simliar issue when setting up our CS:GO hosting service inside a kubernetes cluster. No logs, no errors that mean anything.

The problem we ran into, was due to the fact that our port-forwarding on the firewall/router used a different port than the actual cs:go server that was running. So e.g. you connected from the internet using 23456 but the CS:GO server was running using +port 27015.
For some reason, no one from the internet was able to connect.

So to fix that, we needed to use the same port in the launch options for the cs:go server, as the port that would be used to connect from the internet.