Are you using your router as DNS and DHCP? With Verizon I had a security setting that was blocking public DNS entries to resolving to local addresses. I can't remember what it's called, but it's to prevent a certain type of attack. For a while I disabled it but switching to pihole as DNS, DHCP and using unbound solves it without the security implications
this post was submitted on 08 Mar 2025
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I had the exact same issue. My troubleshooting took me to my router. Nat Loopback and hair pinning.
Your router might have some options relating to NAT loopback or hairpinning. Apparently this can happen if your router recently had an update or if it was restarted abruptly and didn’t boot properly.
Try restarting your router. It didn’t work for me and my router is too basic for those options so in the end I took down my Nextcloud and remade another container and started from scratch. I had all sorts of things fucked with my instance so it just made sense to toss it out and fix it again.
Hope it works for you!
Thanks for the response but restarting the modem/router didn't change anything, nor did creating a new container/NGINX config.
I don't know if this will be of any help, and I dont fully understand the intricacies, but I run into similar issues with my HomeAssistant setup when the certificates expire (every couple of months?). The issue is that HA doesn't pull the new certificate without a reboot, so I typically just restart it every once in a while to ensure that it has the newest certificate.
Thanks, but I don't think that's it. I rebooted and also tried adding a new container to NGINX with a DuckDNS url and it won't load on the local network.
Did you check to be sure that DuckDNS knows your current home external IP address?
Yes and DuckDNS is working flawlessly everywhere except that the network the server is also connected to.
Sometimes DuckDNS goes down partially, their servers breaking for about a week is why I purchased a domain and now host via Cloudflare.
Edit: One of my DuckDNS domains works internally, so at least it's not a systemwide issue. Perhaps one of their relays..
Well like I said DuckDNS is working
What is your router make and model? You need to enable hairpin NAT.
Arris G36 but I don't believe that's the issue as it was working for years before now and on a different router too.
Could also be a stale DNS cache entry on one device or the router. If you ping your duckdns fqdn from the device that can't connect while on your home network, does it resolve to the correct public IP?
I still think a firewall/nat issue is more likely tho.
Hm, pinging works and shows my (external) IP. But no device I've tested can load the duckdns URL.
~~EDIT: Two of the URLS show the local IP replying when pinged. Not configured any differently so I'm not sure what's going on there.~~ This was a PiHole thing apparently
I've got the same problem since a month or two with another dyndns provider. That's not specific to the dydns provider. It is the router. Yet I have no idea how to fix it, and I am too lazy currently.
I'm on graphene, btw.