Internal hostname pointing to private IP is blocked
Many routers and DNS resolvers block public names that resolve to RFC1918 addresses. Meant as a safety, awkward when you need it.
Try this first
- 1Test first: does nslookup return the right IP? If you get the IP but no connection, the block is likely at the DNS resolver or firewall.
- 2On pfSense, OPNsense, Unifi and many SOHO routers this is called DNS rebind protection. Add the domain to the allow list or disable the protection for that domain.
- 3A cleaner fix is split-horizon DNS: let your internal resolver return the private IP and public DNS return nothing. Rebinding protection becomes a non-issue.
- 4Document the exception, otherwise a colleague faces the same puzzle six months from now.
When to bring us in
For Let's Encrypt certificates on internally reachable hostnames or a DNS architecture that is not fully crisp yet, we can sketch the split-DNS design.
See also
- Wi-Fi drops randomly across the officeFirst rule out whether it is the access points or the internet connection itself. Different fix.
- One room or corner has no or bad Wi-FiNot always "add another AP"; often one is poorly positioned, or there is a metal wall in the way.
- Internet is suddenly slow for everyoneThree suspects: your provider, a colleague soaking the line, or a backup or update kicking in unexpectedly.
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