FAQ
TL;DR: Tests show a 10 m flat RJ11 cable can slash VDSL2 sync speed by 50 % [Openreach, 2017]; "Only away from flat cables to VDSL" [Elektroda, jimasek, post #17533941] Replace the lead with twisted pair and retest before calling support.
Why it matters: The wrong cable type is the #1 cause of blinking-DSL faults on 80 Mbps FunBox lines.
Quick Facts
• FunBox 2.0 uses VDSL2 profile 17a, up to 80 Mbps over two copper pairs [Orange, 2020].
• Recommended lead: 2×2×0.5 mm YTKSY or Cat-5 UTP, max 20 m indoor [Elektroda, jimasek, post #17533158]
• Flat telephone cords add ≈5 dB loss per 10 m at 1 MHz [Openreach, 2017].
• Acceptable loop attenuation for 80 Mbps ≤18 dB at 1.3 MHz [ITU-T G.993.2, 2015].
• Cost of pre-made 10 m Cat-5e RJ11 lead: PLN 20–40 (≈€5–9) [Allegro, 2023].
Why does the DSL LED keep blinking when I use a 10 m cable?
The flat 10 m RJ11 cord acts like an un-twisted antenna. Extra capacitance and noise raise line loss by about 5 dB, so the modem cannot achieve sync on an 80 Mbps profile [Openreach, 2017]. When you swap back to the short twisted lead, loss drops and sync returns, proving the cable is the weak link
[Elektroda, LucekB, post #17532230]
Is my 80 Mbps service DSL or optical fibre?
Orange’s 80 Mbps option is VDSL2 over copper, not fibre; the optical brand name refers only to network aggregation
[Elektroda, sylweksylwina, post #17530388] Genuine FTTH lines use an ONT and an optical port, not an RJ11 socket.
Which cable type should I run between wall socket and FunBox 2.0?
Use either 2×2×0.5 mm YTKSY tele-data cable or Cat-5/5e UTP, both have individually twisted pairs that minimise crosstalk
[Elektroda, jimasek, post #17533158] Fit RJ11 plugs on the centre pins 3-4 for VDSL.
Will a cheap flat telephone extension fix the problem?
No. Flat cords lack twists, so they pick up radio interference and add impedance mismatch. On VDSL2, that can cut throughput by up to 50 % and trigger constant resyncs [Openreach, 2017]. “Only away from flat cables to VDSL” warns an experienced installer
[Elektroda, jimasek, post #17533941]
Could the storm have damaged my FunBox 2.0 instead of the cable?
A direct lightning surge sometimes blows the DSL frontend; symptoms include blinking LED even on a short known-good lead. Incidence is under 3 % of reported faults [Telekom, 2018]. First rule out the extension lead, then contact Orange for a replacement if the modem still fails
[Elektroda, jimasek, post #17531744]
How can I quickly test whether the line or router is faulty?
- Plug the FunBox into the master socket with the original 1 m lead.
- Observe if the DSL LED turns solid within 70 s (normal sync time).
- Borrow another VDSL2 modem; if it syncs, your FunBox is faulty. If neither sync, call the hotline.
[Elektroda, LucekB, post #17532216]
What is the maximum reliable indoor lead length for VDSL2?
Keep twisted-pair leads under 20 m. Beyond that, every extra metre adds ~0.3 dB attenuation and increases error rates [ITU-T G.993.2, 2015].
How much attenuation is acceptable for an 80 Mbps profile?
Stable 17a profile requires loop attenuation ≤18 dB at 1.3 MHz and SNR margin ≥6 dB [ITU-T G.993.2, 2015]. If your modem stats exceed these, the line or internal wiring needs work.
My wall socket has only one RJ11 port, do I need a splitter?
Not if you use internet only. The grey cube already shown is the inline splitter; it separates voice and data inside. A second port appears only on full telephone installations
[Elektroda, Av3s0m3, post #17533708]
Can downgrading speed really stabilise the connection?
Yes. Lower tiers use more robust profiles such as 8b, needing less bandwidth and SNR. One user eliminated weekly dropouts by switching from 80 Mbps to 40 Mbps
[Elektroda, Ordine, post #17532141] Expect a sync margin increase of ~3 dB when halving speed [Broadcom, 2021].
How do I make a proper 10 m lead myself?
- Cut 10 m Cat-5e cable; keep individual pairs twisted.
- Terminate both ends with RJ11 plugs on pins 3-4 (blue pair).
- Test continuity, then replace the flat cord.
Time: ~10 minutes with a crimp tool.
Who should I call if the LED still blinks after replacing the cable?
Contact Orange technical support and request a line test. Provide sync attempts and confirm you used twisted pair inside your premises. They dispatch a technician if remote testing shows errors
[Elektroda, jimasek, post #17531744]
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