Direct answer
Double NAT means two routers are translating addresses between your Minecraft server and the public internet. Both layers may need forwarding or one layer must be changed to bridge/access-point mode.
Recommended procedure
- Find the Minecraft host’s LAN address and the WAN address of the closest router.
- Compare the upstream router’s address ranges and identify whether a second router is between it and the ISP.
- Prefer an appropriate bridge/access-point configuration, or forward the same game TCP port through both routers to the correct next hop.
- Check for CGNAT at the ISP separately; forwarding two local routers will not bypass it.
Why this matters
A home connection can have both double NAT and CGNAT. An IP address beginning with a private range on one router does not itself tell you whether the outermost ISP connection is public.
How to verify the result
Test the service from a mobile data network while the Minecraft process is listening. Verify both routers’ firewall rules, not just their port-forwarding UI.
Version and compatibility notes
Do not place the server in an unrestricted DMZ as a default fix. Restrict exposure to the exact game service and keep management interfaces private.
Official references
These sources were checked for the current MSH revision. Version-sensitive details should always be confirmed against the project documentation for the release you run.
Related guides
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