Help with Port Forwarding for Minecraft Server — Previously Worked, Now Doesn’t
Hello, I am having trouble with port forwarding for my Minecraft server. I successfully hosted the server before, and after repeating the same steps, players were able to connect. However, now I followed the exact same steps again, but this time it’s not working and players cannot join.
I have:
Set a static local IP on my server machine
Forwarded port 25565 (TCP) to that IP on my router
Disabled or configured my firewall to allow connections
Tried restarting router and server multiple times
Despite all this, the port still appears closed from external checks, and friends cannot connect.
Could anyone please help me identify what might be wrong or what else I should check?
3 Replies
How long ago was it when it last worked for you?
Is it possible your ISP has started disallowing port forwarding if it was a while ago?
!cgnat
We may have bad news for you :C
You may be under a CGNAT which is a method that ISP's use to conserve IPV4 IP's due to how limited they are now. What this means in plain terms is that your IP address is being shared with other people as your router goes to the ISP's router, by default this means port forwarding doesn't work.
We need to check if you are under a CGNAT and we got 2 options.
Option 1: commands
Depending on your OS, run the following command:
- Windows:
iex (Invoke-RestMethod -Uri "https://raw.githubusercontent.com/DominicTWHV/Is-It-CGNAT/refs/heads/main/windows.ps1")
- Linux: curl -s https://raw.githubusercontent.com/DominicTWHV/Is-It-CGNAT/refs/heads/main/linux.sh | bash
-# You should never run such things without reviewing and understanding the code
Option 2: manually
Open your router's configuration interface. Somewhere, you'll see something like 'external' or 'public' IP.
If your external IP is in one of the following ranges, you're basically screwed as long as port forwards go:
- 10.0.0.0/8
- 172.16.0.0/20
- 192.168.0.0/16
- 100.64.0.0/10
- any IPv6 address/range - This shouldn't be a problem, but Minecraft's IPv6 support is still rather quirky. You're at your own, but we're happy if you share your experience.
What do I do now?
You should ask your ISP for a public and IPv4 address (but this may cost you money).
NB: your internal IP should and most probably will be in one of the first three ranges, don't mix them up