First: Locate Where the Drop Occurs
The most important diagnostic step is determining where in the chain the connection drops. When your internet cuts out next time:
- Check your modem's LEDs. If the "Internet", "WAN", or "Online" LED turns red or off during the drop, your modem has lost its connection to your ISP — the problem is the line or the ISP.
- If the modem LEDs stay green, try to ping your router's IP address from a device (usually 192.168.1.1 or 192.168.0.1). If the router responds but internet is still down, the router lost its WAN connection to the modem.
- If neither the modem nor router appears to drop, the problem may be DNS — try loading a website by IP address instead of domain name.
Common Causes and Fixes
Modem / Physical Line Issues (Most Common for Cable)
Cable internet drops most commonly come from the physical connection between the coax cable and the modem:
- Check all coax connections. Hand-tighten the coax connector on the back of the modem and at the wall plate. Finger-tight isn't enough — use a wrench for a quarter turn past hand-tight if accessible.
- Inspect the coax cable. Look for kinks, cuts, or tight bends. Replace any cable with visible damage with a new RG6 coax cable.
- Check the splitter. If your coax line goes through a splitter (shared with a cable TV box, for example), a failing splitter can cause signal drops. Try connecting the modem directly to the incoming coax line, bypassing any splitters.
- Check modem signal levels. Log into your modem's admin panel (often accessible at 192.168.100.1 for cable modems) and look for downstream power level, upstream power level, and SNR. Values outside the acceptable range indicate a line quality issue that requires an ISP technician.
Router Issues
If the modem LEDs stay green during drops but internet fails:
- Reboot the router by unplugging for 30 seconds and reconnecting
- Update router firmware — stability bugs are frequently patched in updates
- Check if the router is overheating (warm or hot to the touch) — move to a better-ventilated location
- Factory reset the router as a last resort if other fixes don't work
Modem Age and DOCSIS Version
If your cable modem is 4–6+ years old, it may have degraded capacitors that cause intermittent drops under load or in warm temperatures. Older DOCSIS 3.0 modems can also struggle with newer cable plan speeds that require DOCSIS 3.1. A modem that drops regularly but whose LEDs show "healthy" signal levels may simply be failing internally.
ISP-Side Issues
If modem signal levels are out of range, or if the modem is losing synchronization (going through T1–T4 DOCSIS ranging when it reconnects), the problem is on your ISP's infrastructure — either the cable segment between your home and the node, the node itself, or ISP equipment in the area.
How to Document Internet Drops for Your ISP
ISP support is much more effective when you present timestamped evidence rather than vague complaints. Here's how to collect it:
On Windows — open Command Prompt and run:
ping -t 8.8.8.8 >> C:\ping-log.txt
Leave this running. When a drop occurs, you'll see "Request timed out" lines with timestamps in the log file. Stop it after a few days and share the log with your ISP.
On Mac/Linux:
ping 8.8.8.8 | while read line; do echo "$(date): $line"; done >> ~/ping-log.txt
Present this log when calling support. Showing that drops last exactly 2–3 minutes, occur twice per evening, and resolve on their own is strong evidence of an ISP-side problem rather than a device issue.
What to Tell Your ISP
When you call, have ready:
- Timestamps of drops from your ping log
- Duration of each drop
- Confirmation that all devices lose internet simultaneously (ruling out a device issue)
- Confirmation that you tested wired Ethernet (ruling out Wi-Fi)
- Modem signal level readings if available
Request a technician visit to check signal levels at the tap, the coax cable to your home, and any amplifiers or splitters between the street and your modem.
Frequently Asked Questions
Why does my internet keep dropping?
Almost always: modem losing ISP connection due to coax cable issues, modem failure, ISP-side line problems, or router instability. Check modem LEDs during the next drop to locate where in the chain the problem is.
How do I know if it's my modem or my ISP?
Check modem LEDs during a drop. If the Internet/WAN LED goes off, the problem is upstream (ISP or line). If modem stays green but internet fails, the router is the issue.
Can a bad coax cable cause internet drops?
Yes — a loose, corroded, or damaged coax connector is one of the most common causes of intermittent cable internet drops. Check and tighten all coax connections and replace any visibly damaged cable.
How do I document internet drops for my ISP?
Run a continuous ping (ping -t 8.8.8.8 on Windows) and save output to a log file. After a few days, you'll have timestamped evidence of exactly when drops occur and how long they last.
My internet drops every day at the same time. What causes that?
Scheduled ISP equipment restart, peak-hour congestion causing modem desyncing, automated router firmware updates, or a neighborhood interference source that activates on a schedule.