UGREEN exact SKU 25051
2.5 Gigabit Ethernet for a compatible USB-A 3.0 computer
A CM648 multi-gigabit network adapter with the documented RTL8156BG controller, short integrated lead and explicit driver/path requirements.
01 · Product introduction
Overview
UGREEN 25051 USB 3.0 to 2.5GbE Ethernet Adapter (CM648) is a CM648 multi-gigabit network adapter with the documented RTL8156BG controller, short integrated lead and explicit driver/path requirements.
This exact-model guide separates link-rate ceilings from real throughput, explains what the entire cable or radio path must support, and states when operating-system or driver compatibility is conditional.
Research combines exact live UGREEN India product media with exact-model primary UGREEN material. Similar-looking adapters can use different chipsets, radios, speed ceilings and software.
Source reconciliation
Exact sources establish CM648/25051, RTL8156BG, USB-A 3.0 and 10/100/1000/2500Mbps. Official driver availability covers Windows/macOS/Linux, but regional exact guidance says drivers are required on systems other than Windows 11 and macOS, so no blanket plug-and-play statement is made. Exact India material mentions some Android OTG devices; this remains device-dependent. Cat5e can carry 2.5GBASE-T in a qualified channel, while Cat6 is recommended for a predictable new installation. No PoE, VLAN, PXE, jumbo-frame or Wake-on-LAN claim is included.
02 · At a glance
Key features
03 · Connector clarity
Every interface and indicator explained
04 · Performance planning
Link-rate ceilings and real throughput
The RJ45 link ceiling is 2.5Gbps. Real application throughput is lower because of Ethernet/IP overhead, storage, CPU and endpoint limits.
The adapter falls back to 1Gbps, 100Mbps or 10Mbps when any active network component cannot negotiate 2.5GbE.
USB-A 3.0 provides host-link headroom; plugging into USB 2.0 can become the dominant bottleneck.
A complete 2.5GbE route needs a compatible driver, USB 3 host controller, 2.5GbE router/switch/NAS port and qualified four-pair cabling.
Multi-gigabit local transfers can be faster than broadband. An internet test cannot isolate the adapter unless the service and every WAN/LAN port are also faster than 1Gbps.
05 · Complete path
What the host, cable or radio route must support
Use a USB-A 3.0 host port rather than USB 2.0 when aiming above Gigabit.
Use a 2.5GbE-capable router, switch, modem or NAS port.
A qualified Cat5e path can support 2.5GBASE-T; Cat6 is the practical recommendation for a new or uncertain installation.
Install the current exact CM648/RTL8156 driver when the operating system requires it.
Verify the negotiated link at the host and network equipment, then test between capable local endpoints.
06 · Network behaviour
Standards, negotiation and operating roles
RJ45 link modes: 10Mbps, 100Mbps, 1Gbps and 2.5Gbps automatic negotiation.
Exact controller: Realtek RTL8156BG.
The adapter creates one Ethernet interface; router/DHCP equipment normally provides IP, gateway and DNS settings.
The USB-A connection supplies adapter bus power and data only; it is not a charging output or USB pass-through hub.
The RJ45 socket supplies no IEEE PoE or passive power, and no VLAN/PXE/jumbo/Wake-on-LAN promise is made.
Ceiling, not a promise
A port, radio or USB label is a signalling ceiling. Real performance depends on the complete path, protocol overhead, local conditions and the devices at both ends.
07 · Device fit
Compatible devices and systems
08 · Practical value
Use scenarios
09 · Usability
Setup and usability guidance
- Confirm CM648 / SKU 25051 and obtain the exact current driver before removing an existing network connection if needed.
- Connect the USB-A plug directly to a USB 3.0 host port.
- Connect a known-good four-pair Ethernet cable to a 2.5GbE-capable network port.
- Wait for the interface to appear and install the official exact driver when the OS requires it.
- Confirm IP address, gateway and negotiated Ethernet rate.
- Use a fast local 2.5GbE endpoint to test the adapter before relying on an internet-speed result.
10 · Software
Driver and operating-system guidance
Official driver availability covers Windows, macOS and Linux families.
Regional exact guidance identifies Windows 11 and macOS as native-operation cases while other Windows releases may need the exact driver.
Linux support depends on kernel, distribution, CPU architecture, build tools and Secure Boot/module-signing policy.
Android OTG compatibility is conditional on the exact mobile device, OS and physical host adapter arrangement.
Do not market the product as universally driver-free merely because it works natively on one tested OS.
Business-managed systems may block external network interfaces or third-party driver installation.
Driver discipline
Match the exact SKU, chipset, operating-system version and CPU architecture. A driver for a similar enclosure can be incompatible with the hardware inside.
11 · Verified scope
What this product does
- Adds an auto-negotiating 2.5GbE-capable RJ45 interface to a supported USB-A 3.0 host.
- Falls back to 1Gbps, 100Mbps or 10Mbps to match the connected network path.
- Uses the exact documented RTL8156BG controller, 15cm lead and aluminium enclosure.
- Has official driver availability for Windows, macOS and Linux families.
12 · Clear boundaries
What this product does not do
- It does not make a Gigabit-only switch, router, NAS or USB 2.0 host operate at 2.5Gbps.
- It does not provide charging, USB pass-through, video or a USB-C connector.
- It does not supply or receive PoE through RJ45.
- It is not a modem, router, Wi-Fi adapter or network switch.
- It does not guarantee 2.5Gbps application throughput merely from a 2.5Gbps negotiated link.
13 · Best practice
What to do
14 · Common mistakes
What not to do
15 · Read before use
Warnings and limitations
16 · Diagnostics
Troubleshooting by symptom
17 · Exact data
Technical specifications
| Specification | Verified exact-SKU detail |
|---|---|
| Brand / model | UGREEN CM648 / SKU 25051 |
| Product type | USB-A to RJ45 2.5GbE adapter |
| Controller | Realtek RTL8156BG |
| Host connector | USB-A 3.0 |
| Network connector | RJ45 |
| Link modes | 10 / 100 / 1000 / 2500Mbps |
| Integrated lead | Approximately 15cm TPE cable |
| Housing | Aluminium |
| Net weight | Approximately 37g |
| Cabling | Qualified Cat5e possible for 2.5GBASE-T; Cat6 recommended |
| Driver families | Windows / macOS / Linux, exact version-dependent |
| Mobile note | Selected Android OTG devices only; device-dependent |
| PoE / charging / video | Not supported |
Package contents
- UGREEN CM648 / 25051 USB 3.0 to 2.5GbE adapter
- Product documentation
Retail bundles can vary. Ethernet cables, routers, chargers, external power supplies or host adapters are not included unless they appear in the verified list above.
18 · Native collapsible answers
Product-specific FAQ
What exact model does this page cover?
This page covers UGREEN CM648, SKU 25051, the USB-A 3.0 model using RTL8156BG.
What is the highest stated link speed?
RJ45 negotiates up to 2.5Gbps with 1Gbps, 100Mbps and 10Mbps fallbacks; application throughput is lower.
Does it need a driver?
Windows 11 and macOS are listed for native operation; other Windows and Linux setups may need the exact driver.
Which hosts or network devices are compatible?
It supports compatible USB-A Windows/macOS/Linux computers and selected Android OTG devices subject to exact hardware and software.
Will it make my internet faster?
No. It can remove the computer-side link bottleneck but cannot exceed the service, router, switch, cable or server.
Does it support or supply PoE?
No. The RJ45 port neither provides nor receives PoE as an advertised function.
What do its USB or power connections actually do?
The USB-A plug carries host data and adapter power only; there is no charging, video or USB pass-through.
What cable or radio path should I use?
Use a qualified four-pair cable; Cat5e can support 2.5GBASE-T, while Cat6 is recommended for a predictable installation.
Is warmth normal?
Some warmth can be normal. Keep the body uncovered and disconnect it if heat, odour or resets are abnormal.
What should I check first if it does not work?
Check USB 3.0, exact driver, all 2.5GbE endpoints, cable pairs, negotiated rate and a fast local test.
What is included in the box?
The verified base package contains the CM648/25051 adapter and product documentation.
