Loss of Signal
Universal Modem
Severity: CriticalWhat Does This Error Mean?
Loss of Signal means your modem has completely lost the incoming signal from your ISP. With no signal, the modem cannot lock onto any channel or register with the network. This is different from a weak signal — Loss of Signal means the signal is gone entirely. You will have no internet until the signal is restored.
Affected Models
- All cable modems (DOCSIS)
- All DSL modems
- Fiber ONT units
- Arris, Surfboard, Netgear, Motorola, Technicolor modems
- Xfinity, Spectrum, Cox, AT&T, Frontier, CenturyLink subscribers
Common Causes
- The ISP has a service outage in your area affecting the node or street cabinet
- The coax or phone cable has been disconnected, cut, or severely damaged
- Heavy weather has caused physical damage to outdoor cables or equipment
- The modem's line port is damaged after a power surge
- Your service has been suspended or your address is no longer provisioned on the ISP's system
How to Fix It
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Check every cable connected to your modem. For cable internet, verify the coax cable is hand-tight. For DSL, check the phone line. Reconnect anything that looks loose.
An accidental bump can disconnect a coax cable without it being obvious.
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Reboot the modem. Unplug power, wait 60 seconds, and plug back in. This rules out a modem crash rather than a real signal loss.
A modem that has frozen may incorrectly show Loss of Signal. A reboot usually reveals the true state.
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Check your ISP's outage map, status page, or social media. Loss of Signal affecting your whole area is an ISP infrastructure problem, not something you can fix.
Most major ISPs have a real-time status page or a phone hotline for outage reports.
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Check your billing status with your ISP. A suspended account can result in the signal being remotely turned off.
ISPs can deactivate a line remotely if an account is in arrears.
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If you recently had work done in your home (building work, new appliances installed, cable TV work), check whether any cables near the entry point of the line were accidentally cut or disconnected.
Builder damage to incoming cables is more common than you might think.
When to Call a Professional
Loss of Signal almost always requires ISP involvement when it persists after checking cables. Call your ISP and report the loss of signal. Ask them to check the signal level at your modem remotely. If there is no signal on their equipment side, they will dispatch a technician. If signal is present on their side but not at your modem, the fault is in your home — and still something they can usually help diagnose.
Frequently Asked Questions
Is Loss of Signal the same as No Sync?
They are similar but different in severity. Loss of Signal means there is no signal at all coming in. No Sync means there is a signal, but the modem and ISP equipment cannot agree on connection settings. Loss of Signal is generally more serious and more often caused by ISP infrastructure or cable damage.
Can a power surge cause Loss of Signal?
Yes. A power surge can damage the tuner or line port inside the modem. After a storm, if your modem will not pick up any signal and the cables are all intact, the modem itself may be damaged. Try the modem on a friend's connection if possible to rule out modem failure.
How long does a typical ISP outage last?
Most outages caused by equipment failures are resolved within 1–4 hours. Outages caused by physical cable damage (e.g., a digger cutting an underground cable) can take 4–24 hours or more. Your ISP's status page or outage tracker usually provides an estimated restoration time.