The simple hack to boost a Synology NAS to 2.5 Gb/s (without changing the NAS)

Synology NAS have become real nerve centers at home over the years. Backups, multimedia storage, video surveillance, personal cloud, docker services, home automation system, etc… they often do a lot of things at once. But it must be admitted that the configuration could be a bit more robust. I had already upgraded the RAM from 8 to 16Go. But another detail continued to be a bottleneck: the network speed.

Many consumer models are still limited to a Gigabit Ethernet port. On paper, this represents 1 Gb/s, or about 125 MB/s. In practice, we usually get around 80 to 110 MB/s when transferring files. Sufficient in many cases, but as soon as we handle large videos, complete backups, or virtual machines, we quickly hit the limit.

Good news: there is a very simple solution to achieve 2.5 Gb/s on many Synology NAS… without changing hardware. A simple compatible USB network adapter is enough. And the gain can be very pleasant on a daily basis.

Let’s see how to proceed step by step.

1 Gb/s, 2.5 Gb/s, or 10 Gb/s: what difference in practice?

When we talk about home networks, we often think of Gigabit. For years, most internet boxes, routers, and NAS have used an Ethernet connection at 1 Gb/s. For most standard uses, this works very well. But as soon as we handle large files or multiple users access the NAS at the same time, this limit starts to become noticeable.

With a classic Gigabit connection, the maximum theoretical bandwidth is 125 MB/s. In practice, we usually get between 80 and 110 MB/s when transferring files to a NAS.

The 2.5 Gb/s comes precisely to fill this gap between Gigabit and more expensive professional infrastructures. With this speed, the theoretical bandwidth rises to about 312 MB/s, and under good conditions, we often observe 250 to 280 MB/s in actual transfers. In other words, you nearly triple the speed of a standard network without changing the entire infrastructure.

And this is where the 2.5 Gb/s becomes particularly interesting: it typically works with the existing Ethernet cabling, often in Cat 5e. No need to rewire the entire house.

The 10 Gb/s, on the other hand, plays in another category. The speeds can exceed 1 GB/s, which is impressive. But this technology often involves more expensive hardware: specific network cards, pricier switches, and sometimes Cat 6a or better cabling. For a typical home use, it is often oversized.

In practice, the 2.5 Gb/s represents today the best compromise for a home setup or small office. The hardware is becoming more affordable, the installation remains simple, and the performance gain is immediately noticeable.

To give a concrete example, copying a 50 GB archive to a NAS takes about 8 minutes over Gigabit. With a 2.5 Gb/s network, this time can drop to around 3 minutes. When performing regular backups or handling large photo or video libraries, the difference is quickly noticeable.

And it is precisely for this reason that more and more NAS, network cards, and even some internet boxes are starting to directly incorporate 2.5 Gb/s ports.

Prerequisites

The first point concerns the NAS Synology itself.

Not all Synology NAS support 2.5 Gb/s USB network adapters. Compatibility mainly depends on the NAS processor and the support for USB Ethernet drivers in DSM.

In practice, the majority of recent NAS equipped with an Intel or AMD processor work very well with adapters based on the Realtek RTL8156 chipset, such as the one offered by UGREEN.

This compatibility is notably found on many popular models used at home or in small professional installations.

For example, the following models are generally compatible:

The NAS DS720+, DS723+, DS920+, DS923+, DS1520+, DS1522+, DS1621+, DS1821+ work very well with this type of adapter. These are also machines often used for multimedia storage or intensive backups, where the switch to 2.5 Gb/s provides real comfort.

Several models from the DS220+, DS224+, DS423+, or DS423+ series can also work without problems, provided that there is an available USB 3 port.

Some NAS equipped with recent ARM processors may also be compatible, but the results are more variable depending on models and DSM versions.

Conversely, older entry-level NAS or models with only USB 2 ports may present issues. In these cases, even if the adapter is recognized, the performance will remain limited.

If you have any doubts, the simplest is to check two points.

The NAS must have a USB 3 port and use a recent version of DSM (preferably DSM 7 or higher). In the vast majority of cases, if these two conditions are met, the adapter will be recognized without difficulty.

The Plus series NAS are generally good candidates. Here, I have a Synology 1019+ for several years, which is supported.

A little tip along the way: even if your NAS already has two Gigabit ports (like mine), switching to 2.5 Gb/s is often simpler and more efficient than link aggregation. This avoids complex network configurations while providing a higher throughput for a single endpoint.

Next, you need a USB to 2.5 Gb/s network adapter compatible with Synology. One of the most used models is the UGREEN 2.5G USB Ethernet, based on the Realtek RTL8156 chipset. This little box turns a simple USB port into a 2.5 Gb/s network interface. It’s compact, inexpensive, and works very well with DSM once the correct driver is installed.

You must also check the network environment. To truly enjoy the 2.5 Gb/s, your switch or router must of course also support this speed. More and more internet boxes and consumer switches now offer 2.5 Gb/s ports, especially on newer models.

Finally, the computer used for transfers must also have a 2.5 Gb/s network port, otherwise the gain will be limited to Gigabit (if this is not the case, you can also connect a Ugreen 2.5Gbps ethernet dongle).

If these conditions are met, you are ready to move on to the next step.

Installation of the 2.5 Gb/s network adapter

The first step is simply to connect the network adapter to the NAS.

Plug the UGREEN adapter into a USB 3 port on the Synology NAS, then connect an Ethernet cable between this adapter and your switch or router. Physically, the installation takes just a few seconds.

But for DSM to correctly recognize the network interface, you need to install a specific driver.

There is a package developed by the community that adds support for adapters based on the Realtek chipset. This package installs just like any Synology package.

First, you need to determine the type of processor used by the NAS. The official Synology site makes this very easy to obtain:

Here, the processor of my 1019+ is therefore an “Apollolake”.

Then, go to the Github of the package, and choose the right version according to its processor and DSM version: in this case, for Apollolake processor and DSM 7.3.

Once the file is downloaded, open your NAS DSM interface. Go to the Package Center, then choose manual installation of a package. Select the previously retrieved file and start the installation.

The first installation will fail. This is normal, and it is stated on the community GitHub. You then need to go to the terminal (via Putty, for example, by connecting via SSH to the Synology) and run the following command:

sudo install -m 4755 -o root -D /var/packages/r8152/target/r8152/spk_su /opt/sbin/spk_su

Restart the installation of the package as previously. This time the installation should go through.

After a few seconds, DSM automatically adds support for the USB network adapter. We find the package correctly installed:

At this point, a small restart of the NAS as a precaution for the system to detect the new interface should be good.

Then go to the Control Panel, then the Network section. A new Ethernet interface should appear. It corresponds to your 2.5 Gb/s connection.

You can then configure the IP address exactly like for a standard network port, either via DHCP or a static IP according to your configuration.

Checking and testing the 2.5 Gb/s connection

Once the interface is configured, it remains to check that everything works correctly.

In the network settings of the NAS, DSM normally indicates the negotiated connection speed. If everything is correctly connected and your switch is compatible, the displayed speed should be 2500 Mb/s.

This is already a good indicator.

The best test, of course, is a file transfer. For example, copy a large folder from your computer to the NAS. If your PC also has a 2.5 Gb/s interface and the network supports it, the speeds can reach 250 to 280 MB/s depending on the configuration.

In other words, you far exceed the limits of Gigabit.

The gain is particularly visible during complete backups, transferring 4K videos, or when multiple users access the NAS simultaneously.

If the performance seems limited, it might be useful to check a few simple points: the network cable must be at least Cat 5e, the switch must indeed support 2.5 Gb/s, and the computer must also be equipped with a compatible interface.

In most cases, once the adapter is installed, everything works immediately.

Network optimization: getting the most out of 2.5 Gb/s

Once the NAS is upgraded to 2.5 Gb/s, the performance is already well above that of a standard Gigabit network. But a few settings can still improve transfers, especially when handling large volumes of data.

In File Services, on the NAS, SMB, Advanced Settings button, set the maximum SMB to SMB3. Windows 11 handles it very well. And minimum SMB to SMB2, with v1 being outdated.

Few people know it, but the SMB protocol used to access files on a NAS can utilize multiple network interfaces simultaneously. This feature is called SMB Multichannel.

The principle is quite simple. When a NAS has multiple active network interfaces and a client computer also has several, SMB can distribute the data transfer across multiple connections simultaneously. Result: the throughputs can add up.

Let’s take a concrete example. A Synology NAS equipped with two Gigabit ports and a 2.5 Gb/s adapter can theoretically use multiple network links in parallel. If the computer accessing the NAS also has multiple active network interfaces, SMB can distribute the streams and improve performance during transfers.

In some cases, it is even possible to exceed 300 MB/s on a NAS that is only equipped with Gigabit ports… simply because multiple links are working simultaneously.

On recent versions of DSM, SMB Multichannel is usually enabled automatically, but it might be useful to check that the function is indeed active.

To do this, just open the Control Panel, then File Services. In the SMB tab, click on Advanced Settings. The SMB Multichannel feature should be enabled so that DSM can utilize multiple network interfaces.

On the computer side, Windows has natively supported SMB Multichannel since Windows 10 and Windows 11. If multiple network interfaces are available, the system can automatically use them for the same transfer.

However, be careful: this feature mainly brings an advantage when multiple fast network interfaces are available. If your NAS has only one 2.5 Gb/s link and your computer has only one network card, the gain will be limited.

But in a robust installation (multi-port NAS, PC with 2.5 or 10 Gb/s network card, suitable switch), SMB Multichannel can really improve performance during large transfers or when several users access the NAS at the same time.

It’s a small technical detail… but it can make a real difference on an advanced home network.

Finally, don’t forget about the storage itself. A fast network is useless if the NAS disks can’t keep up. On a NAS equipped only with mechanical hard drives, the maximum throughput often hovers around 150 to 200 MB/s depending on the RAID configuration. To fully leverage the 2.5 Gb/s, a volume made up of multiple disks or an SSD cache can make a real difference.

On my 1019+, I have 5 mechanical HDDs. But I have installed two SSDs serving as a cache, which greatly improve performance on frequently used files.

Last small detail that we don’t always think of: the network cabling. Cat 5e cables usually work very well at 2.5 Gb/s, but if your installation is starting to age, switching to Cat 6 can eliminate some stability or speed negotiation issues.

Once these few points are verified, your Synology NAS can truly benefit from the potential of 2.5 Gb/s… and file transfers become much more comfortable right away.

Conclusion

Upgrading a Synology NAS to a 2.5 Gb/s network is ultimately much simpler than one might imagine. A few minutes are enough: a compatible USB adapter, the installation of a driver, and the new network interface appears in DSM.

The performance gain is very appreciable, especially if the NAS is used for large backups, video editing, or shared storage in a small team.

And above all, this solution allows for improved performance of an existing NAS without changing hardware. A small adapter costing a few tens of euros can literally give a second breath to the installation.

A small technical improvement… that really changes daily comfort of use!