Modem Not Working?

Diagnose first — modem fixes are different from router fixes.

The modem connects your home to the ISP. If the modem is the problem, no router fix will help. Signs: modem status lights wrong (LOS red on fibre, no sync on DSL/cable), nothing works at all, just one specific service down.

Most modem issues are software hangs that a 60-second power cycle fixes. Hardware failures (after 3-5 years) usually need ISP replacement.

What this measures

  • Can anything reach upstream?
  • Modem status interpretation

How it works

  1. Check modem lights — see ISP-specific guide
  2. Power-cycle modem 60 seconds
  3. Test

Why this matters

ISP support routinely blames the modem regardless. Having the diagnosis ready lets you push past the script.

Top fixes

  • Power-cycle 60 seconds (NOT 30 — modems need longer)
  • Check LOS light (fibre) — if red, ISP fibre issue
  • If 5+ years old + frequent issues: ask ISP for replacement

FAQs

What does LOS red mean on fibre modem?

Loss of Signal — the fibre line from the ISP is cut or broken. ISP issue, not yours.

Should I replace ISP-provided modem?

Most Indian ISPs require their own modem. Some allow replacement — check terms. Modern ISP modems are usually fine; the bottleneck is router/Wi-Fi side.

Diagnose modem →

Related

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