FAQ
TL;DR: Cat 5e runs carry 1 Gbps up to 100 m [TIA-568 Standard]; “use a small 5-port router and you’re done” [Elektroda, jprzedworski, post #14894933] Put the router/switch where all four cables meet, extend short leads, and patch each room socket.
Why it matters: A single in-wall hub avoids ugly surface wiring and keeps full network speed.
Quick Facts
• Typical 5-port Gigabit switch: PLN 60–90 [Allegro price list, 2023]
• Standard RJ45 keystone needs ≥45 mm box depth [Legrand datasheet, 2023]
• Max Cat 5e channel length: 100 m including patch leads [TIA-568]
• One public IP ⇒ router must perform NAT; extra LAN ports act as 4-port switch [Elektroda, jprzedworski, post #14894933]
• Telephone-grade cable limits speed to 10 Mbps and ≤50 m before errors [Cisco, 2022]
How do I feed the internet to all three wall sockets?
Terminate every in-wall cable on a small router (or switch) inside the junction box where the four cables meet; plug the provider’s cable into the WAN port and the three room cables into LAN ports
[Elektroda, Samuraj, post #14894881]
Do I need a router or just a switch?
If your ISP gives one public IP, you need a router with NAT. The router’s built-in 4-port switch then distributes LAN to each room
[Elektroda, jprzedworski, post #14894933] Multiple public IPs would allow a plain switch.
What if the existing cables are telephone pairs, not Cat5e?
Telephone pairs lack twist density; speeds drop to 10 Mbps and links beyond 50 m can fail outright [Cisco, 2022]. Replace with Cat 5e or use Wi-Fi repeaters as a stop-gap.
My cable stubs are too short. How can I extend them neatly?
- Crimp male RJ45 plugs to each stub.
- Join to new patch leads with compact inline couplers (≤22 mm deep) placed inside the box.
- Punch the far ends into a multi-port faceplate [Elektroda, Dycu, post #14896562]
Are soldered splices acceptable for Ethernet?
Avoid soldering; it changes impedance and often breaks Gigabit signalling. Use keystone jacks or IDC punch-down blocks instead [Fluke Networks, 2021].
Is there a single wall plate with three or four RJ45 outlets?
Yes. Universal 3×RJ45 and 4×RJ45 45×45 mm modules fit standard Polish under-plaster boxes [Morele, product 144218; Elektroda, jprzedworski, #14896645].
Can I hide the switch to keep the wall flush?
Choose a mini 5-port switch (depth ≈ 24 mm) and recess it behind a blank cover; drill three 8 mm holes for patch leads, as suggested in the thread
[Elektroda, Samuraj, post #14894909]
Will a Wi-Fi repeater solve the problem instead of cabling?
Repeaters halve throughput because they retransmit each packet on the same channel; average speed falls 45-55 % in tests [SmallNetBuilder, 2022]. A forum expert called it “the worst you can do”
[Elektroda, hermes-80, post #14896544]
What’s the basic 3-step setup to finish the job?
- Mount a 3- or 4-port RJ45 faceplate in the junction box.
- Punch down each room cable plus ISP lead onto keystones.
- Connect faceplate to a router’s LAN (rooms) and WAN (ISP) using short patch cords.
How long can in-house Ethernet cables be before speed drops?
Cat 5e supports 1 Gbps for 100 m total channel length, including patch leads and couplers [TIA-568].
What edge case could still break the network after rewiring?
If one room cable is wired straight-through but another is reversed (split-pair), the switch may auto-negotiate 100 Mbps yet silently corrupt 1–2 % of packets—enough to stall video streams [Netgear KB, 2021].
Will adding a second switch at another room hurt performance?
Two cascaded Gigabit switches add ≈3 µs latency and no throughput loss for typical home loads [Broadcom, 2022]; fine for splitting to multiple PCs.
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