Is my traffic to my Synology leaving my network?

Jackson Zamorano

7/12/24, 10:43 PM

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 + 2

domain-name-system

routing

synology

Zac67

7/13/24, 8:12 AM

The key is the IP address that you connect your NAS on: local IP is the most direct (and likely fastest) way, public router IP requires a redirect on the router (possibly limiting throughput and increasing latency) and cloud IP requires an additional redirect in the cloud (more throughput limitation and latency increase). However, home networking, consumer-grade hardware and host configurations/issues is explicitly off-topic here, see the [help/on-topic]. You might want to try on [su].

symcbean

7/13/24, 2:07 PM

"The Synology access log does say it was accessed using my public IP" - then there is no port forwarding? Or is there port forwarding and you are applying some intpretation to the data in the Synology logs? If you had shown us the log files we might have understood what you are trying to explain.

Score:1

Server

HBruijn

7/13/24, 7:49 AM

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

+ 1

Greg Askew

7/13/24, 8:23 AM

Could be proxy arp?

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: Is my traffic to my Synology leaving my network?

Post an answer

Most people don’t grasp that asking a lot of questions unlocks learning and improves interpersonal bonding. In Alison’s studies, for example, though people could accurately recall how many questions had been asked in their conversations, they didn’t intuit the link between questions and liking. Across four studies, in which participants were engaged in conversations themselves or read transcripts of others’ conversations, people tended not to realize that question asking would influence—or had influenced—the level of amity between the conversationalists.