Why is Synology QuickConnect so slow? Once you understand the relay principle, it's no longer mysterious. I'll test how to choose between DDNS and DDNS

last month I stayed at a hotel on a business trip. With nothing to do at night, I used my phone to check photos from my Synology DS220+ at home. The page spun in circles for half a minute, photos loaded and blurred, and a larger video was dragged down, with the speed firmly fixed at 3MB/s. But this machine can run SMB on my home's internal network at 110MB/s. How does the same NAS get so broken when you step outside? I only realized the problem was with the QuickConnect relay mechanism, which had nothing to do with the NAS's own performance.

be clear: QuickConnect is not peer-to-peer magic; Synology acts as your intermediary

many people (including myself half a year ago) thought QuickConnect was cutting-edge technology—just enter an ID and you could connect to your home NAS, just like a remote desktop. Breaking it down, it's actually very simple, just three steps:

• NAS at home, every so often I 'check in' to Synology's server, saying I'm online and asking what my address is;
• you enter QuickConnect ID on your phone outside, first ask Synology: Where is this machine?
• after receiving the address, the phone and NAS first try to "punch holes" to connect directly; if the connection fails, the traffic is routed through Synology's relay server.

the first two steps are just matchmaking; the key lies in the third. Drilling holes requires both sides to cooperate with network conditions. Currently, domestic home broadband companies generally do not have public IPv4 IPv4; what you get is a carrier's internal network address starting with 100.64 (which I explained in detail when I wrote public IP self-check ), and the hole drilling success rate is quite impressive. What if you can't get through? Synology lets both of your traffic pass through its deployed relay server: your phone goes to the relay server for one segment, the relay server to your home NAS, and if either of these is poor, the whole route slows down. The so-called "no port forwarding, no public IP needed" comes at this cost.

looking back, most people first encountered QuickConnect when Synology's initial configuration was almost finished, when the Missile Launcher popped up asking you to register a QuickConnect ID, and I clicked that hook off without ever opening that page. Its usefulness lies in the phrase "set once and forget for a lifetime," but the pitfall is that you never know which path you're on right now.

root cause of slowness: relay bandwidth is shared, and there is an invisible ceiling

Once

understand the principle, "why slow" becomes completely mystical; three reasons are stacked together:

First, the bandwidth of the relay server is shared by everyone. Synology forwards data for free, but it won't give you exclusive channels. In practice, it usually caps at 5-10MB/s, and 3MB/s is normal. Flipping through photos and listening to music remotely is enough. If you want to download a few gigabytes of original movies, just wait. I later specifically tested it, and when the same file was relayed, the velocity curve was so flat it looked like an ECG and it died.

here are some of my actual test numbers to give you a feeling: my home has gigabit broadband, 100 Mbps upstream. Internal SMB file transfer 110MB/s; Running relays outside, 3MB/s; Switching to DDNS direct connection stabilizes just over 10MB/s, just enough to fully utilize uplink. Do you get it? — The upper limit for direct connection is your own uplink bandwidth, and the plan you pay for determines it; The relay cap is the small forwarding quota Synology allocated to you; no matter how good your broadband is, it's useless. Spending money on bandwidth but getting stuck at the door of other servers' servers is where the relay loses the most.

second, detours. Data doesn't go straight from your phone to your home; it first leaves the border, then returns to a relay node, resulting in high latency and shaking during evening rush hour. If you're in China and the relay node is overseas, the extra few hundred milliseconds for a round trip translates into a 'click folder and freeze for a moment' in experience.

third, the failure rate of punching holes is underestimated. The more "legitimate home broadband" your home is—no public IP, optical modem, or router mode plus an extra layer of NAT—the easier it is to run through relay year-round. And the process is completely indifferent—the app won't tell you, 'You're currently taking a detour,' so you assume QuickConnect is always this slow, and you're unfairly using your perfectly good NAS.

take two minutes to confirm: are you going to be a reliever or a direct connection

Don't rush to criticize Synology; first confirm your own path. I often use two simple methods:

first, when you're at home or your phone is connected to home WiFi, use the Synology app to transfer a file. Within the same local network, it will automatically connect directly, and the speed should take off directly to intranet level. Taking off at home and going out is slow, basically guaranteeing that going out is a relay.

Second, log in to the DSM backend to check the configuration: Control Panel→ external access→ QuickConnect, click "Advanced" to go to Advanced Settings, where you can see the connection status and select the location of the relay server. Here's a bit of a trap: some people have reported that when someone sits at home, their phone and NAS share the same network, the app occasionally detours to relay the network, and the WiFi gets stuck at full bars. If you encounter this, change the app's connection method to direct connection to the LAN IP directly, so it doesn't let it guess on its own.

also has a simple control experiment: transfer the same file once each from home WiFi and mobile data. The speed difference between the two lanes is several times greater; the slowest lane is probably in the relay. My Synology Drive sync disk used to get stuck and out of sync when going out and that's how I found out—not because the sync task was broken, but because the link was too slow to transmit.

three ways to speed up, arranged according to convenience

first zero-cost rule: in advanced settings, change the relay server's location from "Auto" to the area closer to you, and select domestic or Asia-Pacific nodes for domestic users. After modifying it, my actual test showed it climbed from 3MB/s to around 10MB/s. The improvement is real, but the ceiling is still the relay's ceiling—don't expect a qualitative leap.

The second is IPv6. Nowadays, carrier IPv6 deployment rates are very high. If both your phone and home broadband have V6, QuickConnect can directly connect via V6, and your broadband will run to full speed. How do you turn on the V6 switch on the side of the router? I wrote about it in my article Xiaomi router IPv6, and the paths from other brands like Mercury are pretty much the same. The threshold for this path is "both ends must have V6"—missing one means it's useless.

The third is the right approach: ask the ISP for public IPv4, then use DDNS and port forwarding. I wrote about the pitch for calling customer service in public IP, which usually takes about ten minutes to get it done for free. This setup is the most complicated, but the improvement is qualitative: my home has gigabit broadband, and the external direct connection is stable just over 10MB/s, eating up the uplink completely. It's on a completely different level compared to the 3MB/s relay. Synology's control panel comes with DDNS functionality, and external access → added DDNS →. For service providers, you just need to fill in Synology's own domain name without registering a third party.

How to choose between

QuickConnect and DDNS: One table explains everything, and my answer is both

my actual usage is two things to coexist: DDNS as the main force, fast speed; QuickConnect is the bottom line; if you change network environment, IP drift, or get blocked on ports, it will always connect. Synology's design is truly beginner-friendly, offering free coverage, but the path to safety is slow, so you can't use it as your main weapon.

by the way, to be safe: QuickConnect doesn't open ports, NAS isn't directly exposed to the public network, so the area under scan attacks is small; DDNS+ port forwarding means exposing ports like 5001, so be sure to enable two-step verification and set the default port to a high position. A couple of years ago, ransomware targeted naked NAS systems. I wrote a review of 3,600 QNAP devices encrypted overnight. My device later with three gates , and when I FamilyMart account permission , I did it all at once.

another frequently asked concern: If traffic passes through Synology's relay server, can it see my photo files? Invisible. The relay forwards the encrypted TLS encrypted texts, and Synology's intermediary only handles the packet transfer; without your NAS key, the content cannot be decrypted. This is similar to Feiniu's fn Connect—vendors always position themselves as 'just building bridges, not trust.' If you really mind, you can add another WireGuard tunnel or something yourself, but for home use, it's a bit of a precaution.

Wrap-up: The inspection order is set for you

test the internal network speed at home to rule out problems with the machine itself; If you go out slowly, check if QuickConnect has used the relay; In advanced settings, replace the nearest relay node for free lunch; With a wide V6, just confirm driving on both ends; If you really need to transfer files from external networks, get a public IP for DDNS and get it all in one step. A more comprehensive comparison of the three long-distance routes (including intranet penetration) was first written in the article where connected home NAS, which can be viewed together.