Fix a coax that has no signal

Steps

Goal: Confirm the coax has no signal, then check connectors, splitter, cable, and signal levels.

• Check the modem lights. The downstream or upstream light should be solid when the coax has signal. If those lights are off or blinking and never lock, the coax path has no signal.
• Good: Downstream/upstream off or blinking—coax has no signal. Proceed to Check connectors.
• Bad: Lights solid—different problem (router, Wi‑Fi). See Fix Wi‑Fi that drops or is slow or Fix a modem that drops connection.

Check connectors

Goal: Confirm all coax connectors are finger-tight at the modem, splitter, and wall jack.

• Check the coax at the modem. Hand-tighten the connector—do not overtighten.
• Trace the coax from the modem back to the wall. Confirm every connector along the path is finger-tight—at the splitter, at the wall jack, and where the line enters the home.
• Good: All connectors tight. Proceed to Bypass splitter.
• Bad: Loose—tighten and retest. Power-cycle the modem and check if the lights lock.

Bypass splitter

Goal: Test whether the splitter is causing the no-signal condition.

• If you have a splitter, connect the modem directly to the coax line that enters your home—no splitter in between.
• Power-cycle the modem. Wait for it to attempt sync.
• Good: Modem syncs with direct connection—the splitter is likely faulty. Replace it with a MoCA-compatible or cable-rated splitter.
• Bad: Still no signal—proceed to Inspect cable.

Inspect cable

Goal: Look for damage or corrosion that blocks signal.

• Look for kinks, sharp bends, or crushed coax cable.
• Check connectors for corrosion, bent center pins, or loose center conductors.
• Good: Cable intact. Proceed to check signal levels or call your ISP.
• Bad: Damaged—replace the cable or connector. Use a quality RG-6 coax cable. Retest.

Check signal levels

Goal: Verify downstream and upstream power are in range.

• Log into the modem admin page (often 192.168.100.1 or 192.168.0.1—check the modem label). Find the signal or status page.
• Downstream power should be roughly -7 to +7 dBmV; upstream 35–51 dBmV. Out-of-range levels mean a line or drop issue.
• Good: Levels in range—the coax path is good. The issue may be elsewhere (e.g. modem, router).
• Bad: Levels out of range or no signal—call your ISP. They can test the drop and send a technician.

When to get help

Call your ISP if the modem still has no signal after:

• Checking all coax connectors
• Bypassing the splitter
• Inspecting the cable for damage, and
• Verifying signal levels (if you can access the modem admin)

The problem may be on the drop (the line from the pole or pedestal to your home) or at the tap. Your ISP can test the signal and send a technician.

Verification

• The modem downstream and upstream lights are solid or steady.
• The modem admin shows downstream power roughly -7 to +7 dBmV and upstream 35–51 dBmV. If you have a different modem, check its manual for expected ranges.
• Internet works when you connect a device to the modem or router.