Extend a short patch cable to reach a router, switch, computer or networked display.
RJ45 Female-to-Female Shielded Ethernet Coupler
Overview
UGREEN 20390 is a compact inline coupler for joining two standard RJ45 Ethernet cables into one longer physical run. Each side accepts an 8P8C male plug; internal metal shielding helps reduce interference, and the ABS outer housing protects the connection. The exact model specification rates the coupler for network speeds up to 1000 Mbps and names Cat5, Cat5e, Cat6, Cat7 and Cat8 RJ45 cables. It is passive: it joins conductors but does not switch, split, amplify or create a network.

An inline join—not a switch or signal booster
UGREEN 20390 joins two RJ45 Ethernet cables conductor-for-conductor. It does not create two network outputs, amplify a weak signal, certify cable category or raise the link above 1Gbps. The complete channel performs only as well as its weakest cable, connector and network port.
Key features
- Female-to-female 8P8C RJ45 connection for joining two terminated Ethernet leads.
- Up to 1000 Mbps stated for exact SKU 20390.
- Internal metal shield around the socket path to help control EMI/crosstalk.
- Compatible with standard RJ45 cables sold as Cat5 through Cat8, subject to the total channel.
- Compact ABS housing for home, office, rack or temporary extension use.
- No drivers, configuration or external power required.

Use scenarios
Join two known-good cables temporarily while a correctly sized cable is sourced.
Create a service connection across a desk or test bench without re-terminating a lead.
Place a removable join in a dry indoor low-traffic location.
Reuse existing RJ45 patch cords where a single continuous cable is not practical.

Technical specifications
| Model / SKU | 20390 |
|---|---|
| Connector A | RJ45 female, 8P8C |
| Connector B | RJ45 female, 8P8C |
| Connection type | Passive straight-through inline coupler |
| Maximum stated link speed | Up to 1000 Mbps |
| Cable categories named | Cat5, Cat5e, Cat6, Cat7 and Cat8 with standard RJ45 plugs |
| Shielding | Internal metal shield |
| Outer housing | ABS |
| Power required | None |
| Configuration / driver | None |

Setup and usability guidance
Disconnect or idle network equipment if the link is carrying important traffic.
Inspect both RJ45 plugs for intact contacts and locking tabs; test each cable independently if possible.
Push one cable into each side until both plugs click and cannot be removed without pressing the tab.
Place the join where it stays dry, supported and free from foot traffic or cable tension.
Reconnect equipment and verify link speed and stability; troubleshoot each cable and the coupler separately if performance drops.
Compatible devices and systems
Accepts standard male RJ45 8P8C Ethernet plugs.
The model lists Cat5, Cat5e, Cat6, Cat7 and Cat8 cable compatibility, but the assembled channel performs only as well as its lowest-rated cable, connector, coupler and endpoint.
The exact SKU 20390 listing specifies up to Gigabit Ethernet, so do not use its Cat8 fit as a claim of 10/25/40 GbE performance.

Real-world performance and planning
The coupler adds another pair of contact interfaces to the Ethernet channel. Clean, undamaged plugs that latch fully and two known-good cables give the best chance of a stable link. If speed falls or errors appear, test each cable independently and replace the join with one continuous cable where possible.
Cable-category names describe mechanical compatibility with standard RJ45 plugs; they do not make this 1Gbps coupler a Cat8-performance or 10Gbps component. Total cable length, termination quality, shielding continuity, bends, nearby interference and the capabilities of the router, switch and host all influence the negotiated link.
What this product does
- Provides a straight-through physical join between two RJ45 patch cables.
- Extends reach without cutting or re-terminating either cable.
- Maintains shielding continuity through an internal metal socket structure when the rest of the channel is compatible.
- Requires no power or software.

What this product does not do
- It does not split one Ethernet connection into two devices.
- It is not a network switch, router, repeater, signal booster or media converter.
- It does not upgrade Cat5/Cat5e cable to a higher category.
- It does not guarantee the combined run’s speed or standards compliance.
- It is not specified as waterproof or suitable for exposed outdoor burial.
What to do
- Use cables of the same appropriate category and keep the total channel within the network standard and installation plan.
- Support the joined cables so their weight does not pull on the sockets.
- Verify negotiated link speed after installation and run a real transfer test if performance matters.
- Use a single correctly sized cable instead where maximum reliability or formal certification is required.
What not to do
- Do not confuse a coupler with a one-to-two Ethernet splitter.
- Do not install the join in standing water, direct rain, a crush point or an unventilated high-heat location.
- Do not tug the cables without pressing their RJ45 locking tabs.
- Do not assume that Cat8 plug compatibility means this exact Gigabit-rated coupler delivers Cat8 channel performance.
Check before buying
Both leads must have standard male RJ45 8P8C plugs with working latch tabs.
Plan for a maximum stated link rate of 1000Mbps, not 10Gbps.
Keep the passive join dry, supported and away from foot traffic or cable tension.
For permanent or performance-critical cabling, prefer one correctly sized continuous certified channel.
Warnings and limitations
- Every extra connection adds contact points and can reduce margin on a marginal cable run. A continuous cable is preferable for critical or certified links.
- UGREEN references stable transmission within 50 m, but real limits depend on both cable lengths, category, termination, environment and active equipment.
- The exact product is rated up to 1000 Mbps. A separate newer UGREEN coupler may advertise 10 Gbps; do not transfer that claim to SKU 20390.
- PoE pass-through is not specified for this exact model, so confirm compatibility before using it in a powered Ethernet channel.
Package contents
- 1 × UGREEN 20390 RJ45 female-to-female inline coupler
- Ethernet cables, wall plate, keystone frame, switch and tester are not included.
Product-specific FAQ
Research and source note
This exact-SKU guide was checked against UGREEN India and the applicable official regional UGREEN model page. When official wording or artwork differed, the narrower verified claim was retained; gallery artwork never overrides the written limitations above.
Exact-model and UGREEN India assurance
This description applies to exact UGREEN coupler 20390. Match the SKU, two RJ45 female ports and 1Gbps specification before installation. UGREEN India after-sales eligibility follows the exact listing terms; no higher network rating is implied.
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