FAQ
TL;DR: If your router’s WAN doesn’t have a public IP, 0 port forwards will work; “Without a public IP… redirection just doesn’t work.” [Elektroda, jimasek, post #16983840]
Why it matters: This FAQ shows gamers how to fix LTE/CGNAT port-forwarding so friends can join Minecraft or similar servers.
Quick Facts
- Symptom: Hamachi/Tunngle ping works, but diagnostics say “Inbound traffic blocked” and port tests report “NOT OPEN.” [Elektroda, Hogohin, post #16983730]
- Root cause: LTE modem gives your router a private WAN (e.g., 192.168.8.1), so the ISP firewall/CGNAT stops unsolicited inbound. [Elektroda, Hogohin, post #16983835]
- Fix path: Ask Orange to enable the VPN APN (e.g., vps/vpnbb) to get a public IP for port forwarding. [Elektroda, makosuu, post #16983856]
- Confirmed result: “Problem solved, Orange VPN did the trick.” (public IP + APN change). [Elektroda, Hogohin, post #18723907]
- Router note: ASUS RT-AC51U supports built‑in DDNS for dynamic public IPs. [Elektroda, makosuu, post #16985162]
How do I fix port forwarding for Minecraft when using an LTE modem?
Get a public IP first. Call your operator (e.g., Orange) and request the VPN APN (vps/vpnbb). Reboot the modem, verify the router’s WAN shows a public IP, then forward 25565 to your PC’s reserved LAN IP. Test externally. [Elektroda, makosuu, post #16983856]
Why does Hamachi say “Inbound traffic blocked” even with my firewall off?
Your router’s WAN sits behind the provider’s firewall/CGNAT, so unsolicited inbound traffic never reaches you. Local firewalls don’t matter when upstream blocks it. “Without a public IP… redirection just doesn’t work.” [Elektroda, jimasek, post #16983840]
How can I tell if I have a public IP on WAN?
Open your router’s status page. If the WAN address looks private (e.g., 192.168.x.x) from an LTE modem, you’re not public. That indicates upstream NAT/CGNAT, so forwarding fails until the ISP changes it. [Elektroda, Hogohin, post #16983835]
What APN should I ask Orange for to host a server?
Ask support to enable the VPN APN for your subscription and provide the APN name (e.g., vps or vpnbb). Set that APN on your modem/router, then reboot and re-check WAN IP. [Elektroda, makosuu, post #16983856]
Do I need Hamachi or Tunngle if I have a public IP?
No. With a public WAN IP, reserve your PC’s LAN IP and forward port 25565. Direct connections work without overlay VPNs like Hamachi or Tunngle. [Elektroda, makosuu, post #16983776]
Which port does Minecraft server use by default?
Minecraft Java Edition uses TCP 25565 by default. Forward external 25565 to internal 25565 on your game PC’s LAN IP. [Elektroda, Hogohin, post #16983730]
How do I reserve a static LAN IP before forwarding?
In your router, use DHCP reservation: bind your PC’s MAC to a chosen LAN IP. Reconnect the PC so it receives that IP, then create the port-forward rule to that address. [Elektroda, makosuu, post #16983776]
Dynamic vs static public IP for hosting—what’s better here?
Use a dynamic public IP plus DDNS. It’s cheaper, and your router maps a fixed hostname to changing IPs automatically. Configure DDNS on the router. [Elektroda, makosuu, post #16983894]
How do I set up DDNS on an ASUS RT‑AC51U?
Use ASUS DDNS in the router GUI. 1) Sign in, open WAN > DDNS. 2) Choose ASUS DDNS and create a hostname. 3) Apply, then use that hostname for friends to connect. [Elektroda, makosuu, post #16985162]
My setup is LTE modem + router. Why does port forwarding still fail?
That stack creates double NAT: LTE modem private subnet feeds your router’s WAN. The outer NAT drops unsolicited inbound, so your router’s forwards never trigger. Get a public IP via the VPN APN. [Elektroda, Hogohin, post #16983835]
What is CGNAT, and why does it break hosting?
CGNAT places many users behind the provider’s NAT and firewall. Your router lacks a public IP, so inbound connections cannot initiate to you. Forwarding rules on your router don’t help. [Elektroda, jimasek, post #16983840]
How can I verify the fix worked after switching APN?
Check router WAN shows a public IP, then run an external port test against 25565 while the server is running. Your friends should connect by DDNS or IP. [Elektroda, Hogohin, post #18723907]
Hamachi shows code [208-910-928]—what does that indicate?
That diagnostic appears with an intermediate tunnel and blocked inbound traffic. It matches ISP-side blocking seen with CGNAT before enabling a public IP. [Elektroda, Hogohin, post #16983730]
Edge case: I forwarded the port, but it still closes after a reboot—why?
Your PC likely received a different LAN IP from DHCP. The rule points to the old address. Reserve the IP by MAC, then reboot and retest. [Elektroda, makosuu, post #16983776]
Is there a proven success path for Orange LTE users?
Yes. The thread confirms enabling Orange’s VPN APN, obtaining a dynamic public IP, then using DDNS on an ASUS router resolved hosting fully. [Elektroda, Hogohin, post #18723907]
