Your modem, router, or the line itself is probably failing intermittently
Internet that cuts out and comes back on its own is almost always a hardware problem, not a service problem. The three most common culprits are a failing modem, a failing router, or a line that degrades under certain conditions — usually heat, moisture, or electrical interference. Less often, your ISP's equipment at the pole or in the street is the problem, but you can rule out your own equipment first.
The reason it comes back on is that the device resets itself or the connection re-establishes after the interference clears. This pattern — out for seconds or minutes, then working again — is different from being completely offline, and that difference tells you where to look.
Key Takeaways
- Restart your modem first by unplugging it for 30 seconds, then your router separately, because a modem restart clears the connection to your ISP while a router restart only affects your local network.
- Check whether the outages happen on all your devices at once or only on one device, because single-device problems point to your router or WiFi, while whole-house outages point to your modem or line.
- Look at your modem's lights during an outage — if the internet light goes red or off, the problem is between your modem and your ISP; if it stays green, the problem is your router or WiFi.
- Heat and moisture are the most common causes of intermittent outages, so move your modem and router away from direct sunlight, heating vents, and humid areas like bathrooms.
- If outages stop after you restart your modem but return within hours or days, the modem itself is probably failing and needs replacement.
How to tell if the problem is your modem, router, or line
The fastest way to narrow this down is to watch what happens during an outage. If your modem's internet light (usually labeled "Internet," "WAN," or "Online") goes red or turns off while other lights stay on, the problem is between your modem and your ISP's network. If that light stays green the whole time, your modem is fine and the problem is your router, your WiFi, or the devices themselves.
Next, check whether the outage affects all your devices at once or just one. If your phone loses WiFi but your laptop stays connected, or if one device keeps dropping while others don't, the problem is your router or that device's WiFi card. If everything — WiFi and wired devices — goes out at the same moment, the problem is your modem or the line coming into your house.
Write down the time each outage happens and how long it lasts. If outages cluster around the same time of day, heat or interference is probably the cause. If they're random, a failing component is more likely.
Restart your modem and router in the right order
Restarting fixes about half of intermittent outage problems, at least temporarily. The order matters because your modem connects to your ISP, and your router connects to your modem.
Unplug your modem for 30 seconds, then plug it back in and wait for all lights to stabilize — usually two to three minutes. While you wait, do not touch your router. Once the modem is fully back up, unplug your router for 10 seconds, then plug it back in. Wait another two minutes for it to fully restart.
If outages stop after this restart, monitor how long the fix lasts. If the internet stays stable for days or weeks, something temporary cleared itself out. If outages return within hours, the modem is probably failing and a restart is just a temporary fix.
Check for heat, moisture, and cable damage
Modems and routers are small computers that generate heat. When they sit in direct sunlight, near a heating vent, in a closed cabinet, or in a humid room like a bathroom, they overheat or absorb moisture, and their connections become unstable. Moving them to a cool, dry, open space often stops intermittent outages completely.
While you're moving equipment, look at the cable that runs from the wall to your modem. If it's kinked, crushed, or visibly damaged, that damage can cause intermittent signal loss. The same goes for the power cable — a frayed or loose power connection can cause the modem to reset itself randomly. If you see damage, the cable needs replacement.
Check that all cables are pushed firmly into their ports. A loose connection to the wall outlet or to the modem itself can cause the same on-and-off pattern you're seeing.
Look for interference from other devices
WiFi and cable internet both use radio frequencies that can be disrupted by other devices in your home. Microwaves, cordless phones, baby monitors, and some older wireless speakers all broadcast on the 2.4 GHz band, the same frequency many routers use. When these devices are on, they can cause WiFi to drop or slow down.
Move your router away from the microwave and any cordless phone base stations. If outages happen when you use the microwave, that's your answer — the microwave is interfering with your WiFi. If the outages are affecting your wired devices too, interference is not the problem.
Newer routers can switch to the 5 GHz band, which fewer devices use and which has less interference. If your router has this option in its settings, try switching your devices to the 5 GHz network and see whether outages stop.
When to contact your ISP
Contact your ISP if your modem's internet light goes red during an outage, or if outages continue after you've restarted both devices and moved them away from heat and interference. Tell them the time the last outage happened and how long it lasted. They can check whether their equipment is seeing signal problems on your line.
ISPs can run a line test from their office that shows whether the signal coming into your house is stable. If the test shows problems, the issue is on their side — either the line itself, the equipment at the pole, or the equipment in the street. If the test is clean, the problem is your modem or router.
Ask them to check your modem's signal levels — the downstream and upstream power readings. If these numbers are outside the normal range, your modem may be failing or the line may be degraded. Normal ranges vary by ISP, but your ISP can tell you what yours should be.
When your modem or router needs replacement
If outages stop after a restart but return within a day or two, your modem is probably failing. Modems typically last five to seven years before components inside start to degrade. If your modem is older than that and outages are frequent, replacement is usually cheaper than troubleshooting further.
Ask your ISP whether they provide a modem or whether you need to buy one. Many ISPs include a modem with service, and they will replace it for free if it's failing. If you own your modem, you can buy a replacement from a retailer — make sure it's compatible with your ISP's network type (cable, fiber, or DSL).
Routers fail less often than modems, but the same pattern applies: if outages affect only WiFi devices and restarting the router fixes them temporarily, the router is probably failing. Routers last three to five years on average.
Frequently Asked Questions
Why does my internet come back on by itself?
Your modem or router automatically restarts itself when it overheats or detects a connection loss. This reset clears the problem temporarily, but if the underlying cause — heat, a failing component, or interference — is still there, the outage will happen again.
Can my ISP see that my internet is dropping?
Your ISP can see signal problems on the line coming into your house, but they cannot see WiFi problems inside your home or problems with your router. They can run a line test that shows whether the signal is stable, which tells you whether the problem is their equipment or yours.
Does restarting my modem hurt anything?
No. Restarting your modem is safe and is the first step any ISP support person will ask you to do. It clears temporary connection problems and takes about three minutes total.
What if the problem is only on my WiFi, not on wired devices?
Your router is the problem. Try moving it to a more central location, away from walls and metal objects, and away from other wireless devices. If outages continue, the router's WiFi radio is probably failing and the router needs replacement.
How do I know if my line is bad or my modem is bad?
Ask your ISP to run a line test and check your modem's signal levels. If the line test is clean and signal levels are normal, your modem is failing. If the line test shows problems or signal levels are outside the normal range, the line or ISP equipment is the problem.