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I have a Synology DS723+. I currently have it port forwarded and set up using the Synology dynamic DNS service. It works great, I can access it from outside my network with no problem. However, I cannot determine whether traffic leaves my network when I do try to access it from inside my local network (using the domain name).

The Synology access log does say it was accessed using my public IP, but the speed does not feel any different for using my Synology's local IP (192.168.1.x) vs domain name (xxx.synology.me). I am using 1.1.1.1 for DNS resolution.

If it is leaving my network, how could I get it so that I can use the same address both when I am connected to the network and when I am not WITHOUT my traffic leaving?

Traceroute (sensitive info redacted):

traceroute to xxx.synology.me ([my ip]), 64 hops max, 52 byte packets
 1  [my ip].bois.qwest.net ([my ip])  1.239 ms  0.762 ms  0.704 ms

My network: TP-Link Archer 6 -> Switch -> Synology and MacBook

1 Answers1

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It sounds like you have a typical SoHo setup with a NAT router and port-forwarding of specific traffic from your public IP to servers like your Synology in your LAN.

In most setups your public IP-address is associated with the actual external interface of your router.

Then traffic from your LAN to that public IP-address doesn't leave the external router interface go out to your internet provider, all necessary packet rewriting happens inside of your router. Usually you will get (close to) the same speed and performance as you'd get by directly contacting your Synology via it's internal IP-address.

See for a more detailed schematic Loopback to forwarded Public IP address from local network - Hairpin NAT

HBruijn
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