UGREEN Shielded RJ45 Female-to-Female Coupler (20390)
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. this 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.
- UGREEN 20390
- RJ45 female-to-female
- Up to 1Gbps
- Internal shielding
- Passive • no power
What it does well.
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 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
Extend a short patch cable to reach a router, switch, computer or networked display.
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.
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.
this 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.
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.
- this 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 model, so confirm compatibility before using it in a powered Ethernet channel.
At a glance.
- 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
- In the box
- 1 × UGREEN 20390 RJ45 female-to-female inline coupler
Ethernet cables, wall plate, keystone frame, switch and tester are not included.
Questions buyers ask.
Does this split one internet cable into two?
No. It joins two cables end to end and provides one continuous physical path.
What speed does SKU 20390 support?
The UGREEN India page states up to 1000 Mbps. Overall speed still depends on the complete channel and equipment.
Can I use Cat8 cables?
They can physically connect according to UGREEN, but this coupler’s listed speed remains up to 1000 Mbps.
Does it need power?
No. It is a passive 8P8C inline connector.
Can it boost a weak signal?
No. There is no repeater or amplifier inside. Shorten or repair a marginal run and check active equipment.
Can I use it outdoors?
It is not specified as waterproof. Use it only in a protected dry environment unless placed in a properly rated enclosure.
Will it work with PoE?
PoE pass-through is not specified for this model. Confirm the intended PoE standard and product documentation first.
Why did my link negotiate below 1 Gbps?
Test each cable, check all eight conductors, inspect plug contacts and compare the total run; the weakest component controls the result.
Is it a keystone jack?
It is a compact inline female-to-female coupler. Fit in a particular wall plate or keystone frame is not verified.
Should I use a coupler or one long cable?
A coupler is convenient for extension, but one correctly terminated continuous cable generally offers fewer failure points for critical links.
Does Cat8 compatibility mean a 10Gbps or 40Gbps link?
No. this SKU is stated up to 1000Mbps. Cat8 is named as an RJ45 plug/cable compatibility category, but the coupler does not raise its own link-speed ceiling or certify the assembled channel.
Can the coupler be installed outdoors?
It has no weatherproof or waterproof rating in the model information used here. Place it in a clean, dry indoor location or inside a suitable rated enclosure, with strain relief on both cables.
This description applies to UGREEN coupler 20390. Match the SKU, two RJ45 female ports and 1Gbps specification before installation. UGREEN India after-sales eligibility follows the listing terms; no higher network rating is implied.