How to Know Your Modem Is Going Bad
A failing modem usually shows itself through dropped internet, slow speeds that don't match your plan, or devices that won't connect at all. The most reliable way to tell is to restart it—unplug the power cable for 30 seconds, plug it back in, and watch the lights. A healthy modem shows a solid or blinking green light on the internet or online indicator within two minutes. If that light stays red, orange, or off after a full restart, your modem is not connecting to your internet service provider and likely needs replacement.
Not every connection problem means your modem is broken. Your router, your devices, or your internet service itself could be the culprit. But a modem that fails the restart test, shows physical damage, or loses connection repeatedly in the same way is almost certainly the problem.
Key Takeaways
- Restart your modem by unplugging it for 30 seconds, then watch for a solid green light on the internet indicator within two minutes—if it stays red or orange, the modem is likely bad.
- Repeated loss of connection, speeds far below what your plan promises, and devices that cannot connect at all are common signs of a failing modem.
- Check the physical modem for burn marks, melted plastic, or a burning smell, which indicate hardware failure.
- Modems typically last five to seven years; if yours is older and failing, replacement is usually cheaper than repair.
- Contact your internet service provider to confirm the modem is the problem before you buy a replacement, since they may provide one at no cost.
The Restart Test and What the Lights Tell You
The restart is the first and most important test. Unplug the modem's power cable completely—not just turn it off with a button. Wait 30 seconds. Plug it back in and watch the lights on the front.
Within 30 seconds, you should see lights begin to flash. Within two minutes, the internet or online light (usually labeled "Internet," "Online," or with a globe symbol) should turn solid green or settle into a steady pattern. If it does, your modem connected to your service provider. If the light stays red, orange, or off after five minutes, the modem is not connecting and is likely defective.
Write down which lights are on and what color they are. When you contact your internet service provider, they will ask you this. The power light should always be on. The internet light should be green or blinking green. Lights for individual devices (usually labeled 1, 2, 3, or 4) should be off unless a device is actually plugged in and using the connection.
Connection Drops and Slow Speeds That Point to Modem Failure
A modem that loses connection once a week or once a month might be overheating or developing a bad capacitor. A modem that drops connection multiple times a day, or that loses connection for 10 to 30 seconds at a time, is almost certainly failing. Note when the drops happen—morning, evening, during heavy use—and how long they last. This information helps your service provider rule out other causes.
Slow speeds are trickier to diagnose because many things can cause them. But if your plan promises 100 megabits per second and you consistently measure 10 to 20 megabits per second, and a restart does not fix it, the modem is a likely culprit. Use a speed test website like Speedtest.net or Fast.com on a device connected by ethernet cable directly to the modem (not through your router). If the speed is still far below your plan, the modem is not delivering the signal properly.
Devices that cannot connect to the modem at all, even after a restart, also suggest modem failure. If one device cannot connect but others can, the problem is the device, not the modem. If no devices can connect, or if devices connect but when ready drop, the modem is the problem.
Physical Damage and Overheating Signs
Look at the modem itself. Burn marks, melted plastic, or discolored areas on the case mean the modem has overheated or had an electrical failure. A burning smell when the modem is plugged in is a serious warning—unplug it when ready and do not use it again.
Feel the modem's case (not the ports) after it has been running for 10 minutes. It should be warm but not hot enough that you cannot hold your hand on it comfortably. If it is too hot to touch, it is overheating. This can happen if the modem is in a closed cabinet, in direct sunlight, or if the internal fan is clogged with dust. Try moving it to an open, cool spot and restarting it. If it still overheats, the internal cooling system is failing and the modem needs replacement.
When to Contact Your Internet Service Provider
Before you buy a new modem, contact your internet service provider. Tell them the modem is not connecting, or that the internet light is red after a restart. Many providers will send a replacement modem at no cost, especially if the modem is one they provided when you signed up. Some providers rent modems to customers; if you own yours, you will need to buy a replacement yourself.
Your service provider can also run a line test from their end to see if the problem is the modem or the connection coming into your home. They may ask you to restart the modem while they watch the signal on their side. This takes 10 to 15 minutes and can save you the cost of replacing a modem that is actually working fine.
If your service provider confirms the modem is bad, ask whether they provide a replacement or whether you need to buy one. If you need to buy one, ask them which models work with your service and your internet speed. A modem rated for 300 megabits per second will not deliver 500 megabits per second, even if your plan includes it.
Modem Age and When Replacement Makes Sense
Modems typically last five to seven years. If yours is older than that and showing signs of failure, replacement is almost always the right choice. Repairing a modem is rarely possible for home users—most repairs require soldering or replacing internal components—and repair shops charge $75 to $150 for diagnosis alone.
A new modem costs $50 to $150 depending on the speed it supports. If your modem is five years old and failing, buying a new one is cheaper than paying for a repair diagnosis. If your modem is two years old and failing, contact your service provider first, because they may replace it under warranty or as part of your service agreement.
When you do replace the modem, keep the old one until you confirm the new one works. Some service providers want you to return the old modem; others let you keep it. Check your service agreement or ask when you order the replacement.
Frequently Asked Questions
Can a modem be bad even if the lights look normal?
Yes. A modem can have a bad ethernet port, a failing internal component, or a software glitch that does not show up in the lights. If the lights are normal but you have constant connection drops or very slow speeds, restart the modem and run a speed test. If the problem persists, contact your service provider to test the line.
What does it mean if the internet light blinks instead of staying solid?
A blinking internet light usually means the modem is working but data is moving across the connection. This is normal during use. If the light blinks constantly even when you are not using the internet, or if it blinks very slowly (once every few seconds), the modem may be struggling to maintain the connection. Restart it and see if the pattern changes.
Is it safe to keep using a modem that overheats?
No. An overheating modem can fail suddenly and may pose a fire risk if the overheating is severe. Move it to a cooler, open location and restart it. If it still overheats, stop using it and contact your service provider for a replacement. Do not leave an overheating modem plugged in unattended.
Do I need to buy the exact modem my service provider originally gave me?
No. You can buy any modem that is compatible with your service provider and supports your internet speed. Your service provider can tell you which models work with their network. Buying a modem from a third party is often cheaper than renting one from your service provider over time.
What should I do with my old modem after I replace it?
Check your service agreement or contact your provider to see if they want it back. If they do not, you can recycle it at an electronics recycling center or donate it if it still works. Do not throw it in the trash, as modems contain materials that should be recycled.