Some PCs cannot access server localy

Dear everybody,

I am facing a very annoying failure with my nextcloud snap install. When I try to connect to my server with my desktop computer with the https address of my server I have a timed out error from my browser. I am having the same issue when I try to connect with the phone app.
The thing is that everything was working fine before I reboot my station. But this only happens when I am connected to the same internet connection (so local) but I can connect with the local IP of my server. The other thing is that all my other computers are able to connect with the https address with the local connection.
I have been looking for many days now and I can’t find the solution.
If anyone has anything to propose…

That sounds like a classic DNS problem.

I’ll bet that what’s happening is that your (external) DNS is telling the world that your IP is a.b.c.d, but your internal IP is e.f.g.h. That means you can access it by using the internal IP locally but your address is only available externally.

Does that make sense?

Your external DNS is pointing to your router (or real-world IP address), which forwards requests to your Nextcloud. However, internally your DNS is pointing you to your router, so it throws an error. But your internal IP address works because it points to your machine.

I’m making assumptions here, but your situation is VERY familiar, I had exactly the same issue. It was solved by running an internal DNS which could direct local machines to the right servers. (Pi-hole will also solve this!)

The way around this depends on your specific situation. Desktops can have the address/IP added to its hosts file, but laptop can leave the local network, so hosts isn’t ideal.

Browsers/machines can cache addresses, so a reboot may have been the point where your computer reloaded the wrong address from the DNS server. DNS issues are an infamous problem on local networks.

I hope this helps, and gives you something to think about!

If you do a DNS lookup of your address
Do you get the local IP or the public IP?

Normally this type of issue is resolved with split horizon DNS. Have you set that up on your local network?

Dear DarkSteve,
Thank you for your very clear answer. Now I anderstand my problem very well.
I am looking actively for a solution to this if you have any suggestion, you are welcome.

best regards


Hey thank you for the answer,
I see my public IP and my ipv6 IP