docs: add "Overlapping IPs for Resources" how-to

[SunsetDrifter]

Summary

New Networks use-case guide at /manage/networks/use-cases/overlapping-ips-for-resources, plus its sidebar entry under Networks → Use Cases (after "Reach Services on the Routing Peer").

The guide owns the overlapping-IPs problem end to end: it opens with the symptom and root cause (a shared address can only ever resolve to one site, single-winner route selection), then presents the fixes as a decision ladder in order of preference:

1. Install the NetBird client on the resource device itself, dissolving the overlap
2. Route selection, when one site at a time is enough
3. Renumbering one site, the durable fix when broad access to many services is needed
4. A small nginx stream proxy on each site's routing peer, for reaching both sites at once when the devices can't run the client

It also names the two paths that look right and aren't (the built-in Reverse Proxy and custom NAT remapping) and why.

Only the last rung gets the full how-to treatment: proxy bound to the peer's NetBird IP so each site is reached by its own peer name, least-privilege policies scoped to the proxy port, common nginx pitfalls (module missing, block placement, boot ordering, peer re-registration), an optional custom DNS zone with CNAME records for friendly per-site names, and honest limits (per-service cost, no automatic failover of the proxy path, LAN-side listener exposure, TLS name expectations).

Summary by CodeRabbit

• New Features
  • Added a new guide for accessing resources in networks with overlapping internal IP/port addresses, including recommended solutions, verification steps, and optional custom DNS naming.
• Documentation
  • Improved the on-site documentation navigation to better surface the new guide and related troubleshooting sections.

[coderabbitai]

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Review details

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 27322dd6-6718-4a1e-ac9d-2c04323e19f5

📥 Commits

Reviewing files that changed from the base of the PR and between efb929f and cff5a56.

📒 Files selected for processing (2)

• src/components/NavigationDocs.jsx
• src/pages/use-cases/remote-access/overlapping-ips-for-resources.mdx

📝 Walkthrough

Walkthrough

This PR adds a new MDX guide for overlapping internal IPs and updates several navigation entries in NavigationDocs.jsx, including a link to the new page.

Changes

Overlapping IPs guide and navigation

Layer / File(s)	Summary
Navigation entries reformatting and new link src/components/NavigationDocs.jsx	Reformats the new guide link plus existing troubleshooting/help entries into multiline object literals without changing titles or hrefs.
Guide introduction and problem scenario src/pages/manage/networks/use-cases/overlapping-ips-for-resources.mdx	Adds the page description, the overlapping-IP problem setup, an example with two sites, and prerequisites.
TCP proxy setup steps src/pages/manage/networks/use-cases/overlapping-ips-for-resources.mdx	Describes the nginx stream proxy setup, listener-scoped access policies, and client connection flow using routing peer names.
Verification, optional DNS, and limits src/pages/manage/networks/use-cases/overlapping-ips-for-resources.mdx	Adds verification steps, optional CNAME-based DNS aliases, and the documented constraints of the pattern.

Estimated code review effort: 2 (Simple) | ~10 minutes

Possibly related PRs

• netbirdio/docs#766: Both PRs touch the docs navigation and adjacent MDX content for the same docs area.
• netbirdio/docs#773: Both PRs modify src/components/NavigationDocs.jsx entries under MANAGE NETBIRD → Networks → Use Cases.
• netbirdio/docs#796: Both PRs update the same docsNavigation structure in src/components/NavigationDocs.jsx.

Suggested reviewers: TechHutTV

Poem

A bunny found two sites with one IP,
Then hopped through nginx streams so merrily,
With peer names, CNAMEs, docs aligned,
The routes stayed calm and neatly lined. 🐇

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly matches the main change: adding a new how-to guide for overlapping IPs for resources.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch docs/reach-two-sites-same-ip

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