Unable to reach public IPv4 addresses on the local network (complex issue)
Unable to reach public IPv4 addresses on the local network (complex issue)
Hey everyone, the topic might seem easy, but it really surprised me and I need some help. My setup includes a local server that I can reach using its IP address. I've also created a domain with DNS to connect to my server over the internet. It functions well when I'm not connected to my local network. The unusual part is that I can partially access my server through my domain in my local network. Only small data transfers work, but large ones cause my router to crash. For instance, using Nextcloud, backing up contacts and videos (about 30MB) causes my router to fail at 10-20%. I also noticed I can't ping my public IP addresses. Recently, I spoke with my internet provider (UnityMedia Germany) who said it's not possible to reach my public IPv4 address because the router can't handle it and thinks it's an attack. They insisted this isn't feasible at all. This seems pretty strange to me. My question is: Can you really ping your own IPv4 address from your local network? Are there any internet providers that allow this? Or is their equipment just unreliable? Thanks in advance for your responses, Matze.
Your router is just shit, simple as that. There is no reason why you couldn't ping your public IP from within your local network other than whatever your router has been configured to do. You could replace it with a better one. pfSense is a really great router OS, if you're willing to build your own and learn a little on how IP-networking works.
It's referred to as hairpinning or NAT loopback, as @Levent mentioned—it doesn't relate to the router malfunctioning. It's typically disabled by default since it tends to create more issues than benefits in about 99% of situations. Many companies view it as a security concern as well.
I thought something similar. Yeah, thank you all for your fast responses. Now I'm searching for a new router.
No device currently offers NAT loopback support; it remains a complex issue with limited practical solutions.
Looking for a budget router that works this way can be tricky. The main concern is why exposing such a security issue affects so many people who don’t actually need it.