Login or Register

Networking

Port forwarding works internally but not from the internet

troublesync_editorial
4w ago
Security
Environment

Environment

Home server behind an ISP-provided router with a second mesh router.

What happens

What happens

The service opens through the public hostname on LAN but external connection tests time out.

What I have tried

What I have tried

Forwarded the port on the mesh router and allowed it through the server firewall.

I would appreciate advice on how to identify the root cause without risking existing data or configuration.

Post timeline
COMMUNITY RESPONSES

Verified community troubleshooting

1 reply
0
ida_innovates Answer
user
Posted 2w ago • 0 confirmations

This looks less like a hardware failure and more like a configuration issue.

Likely cause: Double NAT or carrier-grade NAT prevents the public connection from reaching the inner router.

What I would try: Compare the router WAN address with the public address, bridge one router and request a public IPv4 address or use a secure tunnel.

Keep an eye on the relevant logs during the test; they should confirm whether the hypothesis is correct.

Showing 1 of 1 community responses
AI DIAGNOSTICS

Incident analysis

Updated 4w ago• Trouble ID

Most likely causes

Double NAT or carrier-grade NAT prevents the public connection from reaching the inner router. 76%
A recent software, firmware or configuration change is exposing an existing compatibility issue. 30%

Summary

The reported behaviour is consistent with double NAT or carrier-grade NAT prevents the public connection from reaching the inner router. The safest next step is to verify that hypothesis with a reversible test before making permanent configuration changes.

Suggested Fixes

Verify the likely cause
Compare the router WAN address with the public address, bridge one router and request a public IPv4 address or use a secure tunnel.
Validate and monitor
Reproduce the issue once after the change, review relevant logs or metrics, and keep a rollback path until the system has remained stable.

Continue troubleshooting

Related troubles

Matched from the title, description and tags

Edit trouble

Changes are recorded and can be restored later.

Tags · choose up to 10

Edit answer

Improve accuracy, clarity, and reproducibility.

Answer contentMarkdown

Report this trouble

Reports are private and help moderators keep the community useful and safe.

What is wrong?
Misuse of reports may restrict this privilege.

Revision history

Every entry contains the version that existed before that change.

No edits have been made yet.
Contact • Help • API Docs • Careers • Terms • Privacy • Cookies • Ads