Internet that keeps cutting out — disconnects every 15 minutes, drops during video calls, restores itself a minute later, repeats forever — is one of the most frustrating problems because it never happens long enough to investigate fully. The cause is almost always one of: a dying router, signal interference, an ISP-side line fault, or a DHCP lease issue. Diagnosing systematically saves hours of random testing. We go deeper on the whole subject in our Complete Guide to Fixing Windows, Browser, and Software Errors.
First diagnostic in 30 seconds: when the next drop happens, look at your router’s LEDs. Does the WAN/internet light go off briefly, or do the local network lights blink? WAN off = ISP-side or modem issue. WAN steady but LAN flickering = your local network or router. This single observation cuts the troubleshooting space in half.
Reboot the modem and router properly
“Have you tried turning it off and on again” is the eternal joke, but it actually works for intermittent disconnects more than any other quick fix. Here’s the right way:
- Unplug both modem and router from power (not just turn off — physically unplug)
- Wait 60 seconds. Yes, the full minute. Capacitors discharge, IP leases expire on the ISP side, internal state resets fully
- Plug the modem back in first → wait until all its lights stabilise (usually 2-3 minutes)
- Then plug the router in → wait another 2 minutes for it to fully come online
- Test connection
If drops stop for hours/days after this sequence: the equipment was in a stuck state. If they resume within minutes or hours, the underlying cause persists and needs deeper investigation.
Check for ISP-side issues
Before assuming the problem is yours, rule out the ISP. Most providers have status pages or apps:
- UK: BT Service Status, Sky Service Status, Virgin Status pages
- US: Xfinity status, AT&T outage center, Verizon services
- Independent: downdetector.com — shows real-time user reports for major ISPs
If multiple users are reporting problems in your area, it’s network maintenance, line work, or congestion. Nothing you can fix at home — you wait it out.
For chronic intermittent drops, call the ISP with concrete logs: timestamps of each drop over a week, durations, what activity was happening. Most ISPs can run a line test remotely that detects faults invisible from your end. “My internet drops sometimes” gets brushed off; “It dropped 14 times between 7-11pm Tuesday, mostly for 30-60 seconds each, while I was on video calls” gets attention.
Modem health and SNR margins
If you have access to the modem’s admin page (often 192.168.100.1 for cable modems, or your gateway IP), look for “Signal Status” or “Line Status.” Key numbers to check:
| Metric | Good range | Problem range |
| Downstream Power (cable) | -7 to +7 dBmV | Outside ±10 dBmV |
| Upstream Power (cable) | 35-49 dBmV | Above 51 dBmV |
| Downstream SNR | 35+ dB | Below 30 dB |
| DSL Line attenuation | Below 30 dB | Above 60 dB |
If your numbers are in problem ranges, that’s a physical line issue. The modem can’t maintain a stable connection because the signal quality from outside isn’t good enough. Only the ISP can fix this — they need to send a technician to check the line from your house back to their network.
Wi-Fi vs wired test
If only Wi-Fi devices drop and Ethernet stays connected: the issue is Wi-Fi specifically, not internet. Different fix path. If both Wi-Fi and Ethernet drop simultaneously: it’s the router, modem, or ISP.
Plug a laptop directly into the router with an Ethernet cable. Run a continuous ping to a stable external server: ping -t 8.8.8.8 in Command Prompt. Leave it running. When the next drop happens, look at the ping output. If the wired connection didn’t lose a single ping during the same time Wi-Fi devices disconnected: definitely Wi-Fi. If wired lost pings too: shared root cause.
This single test isolates a huge category of intermittent issues — many “internet keeps cutting out” complaints are actually “Wi-Fi keeps cutting out,” and the fix is on the wireless side, not the internet connection itself.
Our guide on Wi-Fi keeps disconnecting covers the wireless-specific issues in detail, and our router drop troubleshooting covers the router-side fixes. For ISP-side line quality and connection stability information, ThinkBroadband’s speed testing tools include line monitoring that can verify chronic connection problems with timestamped logs.
DHCP lease and IP renewal
Devices on your network get IP addresses from the router via DHCP. Each address comes with a lease time. When the lease expires, the device asks for renewal. If renewal fails — even briefly — you lose connection until it succeeds on retry.
Default DHCP lease times are often 1 hour or 24 hours. If you have drops happening at very regular intervals (like exactly every hour), DHCP lease renewal failing is the likely cause.
Fix: router admin → DHCP settings → increase lease time. Settings to 7 days or even longer for stable home networks. With less frequent renewals, less chance for one to go wrong.
Permanent fix for specific problem devices: assign them a static DHCP reservation. Router admin → LAN → DHCP reservations → “Add static lease” → bind the device’s MAC address to a specific IP. The device always gets the same IP without DHCP negotiation. Useful for desktops, NAS, game consoles.
Router temperature and age
Consumer routers run hot and are usually passively cooled. Capacitors and the wireless chipset degrade over time, especially in warm environments. A router that’s 5+ years old and runs warm/hot to the touch is a common cause of intermittent disconnects, even if it worked fine when newer.
Easy diagnostic: put your hand on the router. Noticeably warm to hot? It’s probably overheating, throttling, and dropping connections to recover. Move it somewhere with airflow — out of the TV cabinet, off the floor, away from other heat sources. A cheap USB fan helps.
If drops stop after improving ventilation, you’ve found the cause. Long-term, plan to replace the router — heat damage is cumulative; even with better cooling, an older unit is on borrowed time.
Firmware updates
Router firmware updates fix actual bugs that cause intermittent disconnects. Many home routers ship and never get updated, sitting on firmware from years ago with known stability issues.
Check: router admin → Firmware / Administration / System tab. If an update is available, install it. The update takes 3-5 minutes during which the network goes down — don’t unplug the router during this. After update, observe for 24-48 hours. Disconnect issues that were firmware bugs simply stop.
ISP-issued routers (Sky Hub, BT Smart Hub, Virgin SuperHub) update through the ISP automatically. If yours hasn’t been updated for a long time and drops persist: call the ISP and ask them to push the latest firmware — they can usually do this remotely.
DNS server changes
When the ISP’s DNS goes flaky, websites won’t load even though your actual internet connection is fine. The drop appears total because nothing works, but really only DNS is broken.
Switch to public DNS as a permanent fix: Settings → Network → your connection → DNS server assignment → Manual → enter:
- 1.1.1.1 and 1.0.0.1 (Cloudflare — usually fastest)
- 8.8.8.8 and 8.8.4.4 (Google)
- 9.9.9.9 (Quad9 — adds malware filtering)
Public DNS is more reliable than most ISP DNS, and frequently faster too. After switching, websites resolve even when the ISP’s DNS is having an off-day.
Specific drop patterns
| Pattern | Most likely cause | What to do |
| Drops every 15-60 min, consistent | DHCP lease or ISP session timeout | Increase DHCP lease; contact ISP about session timing |
| Drops during peak hours only | ISP congestion or QoS limits | Document with timestamps; call ISP if frequent |
| Drops only Wi-Fi, Ethernet fine | Wi-Fi channel interference | Change Wi-Fi channel; move router away from interference |
| Drops everything simultaneously | Router, modem, or upstream issue | Reboot cycle; check modem signal levels |
| Drops correlate with weather | Outdoor cable or junction water ingress | ISP needs to inspect physical line |
| Drops after device wakes from sleep | Device-side network adapter sleep | Device Manager → network adapter → power management → disable sleep |
The single most important diagnostic question: “Does only Wi-Fi drop, or does Ethernet drop too?” That answer points to entirely different fix paths and saves you from troubleshooting the wrong thing.
Network adapter sleep mode
Windows aggressively saves power by putting the network adapter to sleep during idle periods. When you start using the internet again, the adapter has to wake — and during the few hundred milliseconds it takes, you can experience a tiny “drop.” On older laptops or with flaky drivers, the adapter sometimes fails to wake cleanly, leading to longer disconnects.
Fix: Device Manager → Network adapters → your adapter (the one used for active connection — Wi-Fi or Ethernet) → Properties → Power Management tab → uncheck “Allow the computer to turn off this device to save power” → OK.
For Wi-Fi specifically, also check: Network adapter → Properties → Advanced tab → look for “Power Save Mode” or “Wireless Mode” → set to “Maximum Performance” instead of any battery-saving setting. Some Wi-Fi cards default to aggressive power saving that causes brief drops.
Caveat: on a laptop running on battery, this slightly reduces battery life. Worth the trade-off if drops are frequent enough to interfere with work.
Cable and connector check
Physical connections degrade over time. Bent ethernet cable, loose connector, oxidised contact point, frayed coax cable at the modem — all of these cause intermittent issues that masquerade as “internet problems.”
Quick visual inspection:
- Coax cable to modem: connector tight? Centre pin straight? Cable not bent at sharp angles?
- Ethernet cable: clip on the connector still intact? Cable not stretched or bent excessively?
- Power adapters: warm but not burning? No visible damage to the cable?
If any cable looks compromised, replace it. Generic ethernet cables are £5-£10; coax cables similar. Cheapest possible fix to rule out if cable damage is the issue.
Wiggle test: while running a continuous ping, gently move the cable at each connector. If pings drop while wiggling, you’ve found the bad connection. Re-seat firmly or replace.
Identify other connected devices misbehaving
One faulty device on the network can cause issues for everything. A printer constantly broadcasting; a smart device stuck in a connect loop; a phone repeatedly trying to negotiate; an old IoT device with a broken Wi-Fi stack hammering the router with retry traffic.
To check: in the router admin, look for “Attached Devices” or “Client List.” See how many devices are connected, and what they’re doing. If you see something you don’t recognise, or a device showing unusually high traffic when it shouldn’t, that’s suspicious.
Quick narrowing test: turn off everything except one device (say, your main laptop). Does the connection stabilise? If yes, something on your network is the troublemaker; reintroduce devices one at a time to find which.
Common offenders: old smart bulbs from defunct brands; cheap IP cameras; second-hand smart speakers stuck on an old firmware; mesh nodes that lost their pairing. Updating, factory-resetting, or removing the device usually fixes the wider network instability.
When patterns reveal the cause
Document drops over a week:
- Time of day each occurred
- Approximate duration
- What was happening (gaming, video call, idle, large download)
- Which devices affected (all, just Wi-Fi, just one device)
Patterns emerge quickly. Drops only during evenings → ISP congestion. Drops always at the top of each hour → DHCP lease. Drops only during peak Wi-Fi use → router can’t handle the throughput. Drops when the smart fridge cycles → 2.4 GHz interference. Drops only with specific devices → that device’s network stack is broken.
This kind of documentation is also exactly what ISPs need to take chronic issues seriously. “It drops sometimes” isn’t actionable; “It dropped at these specific times under these specific conditions” is.
When to give up and upgrade
Routers and modems have lifespans. After 5-7 years of constant use, they degrade — capacitors weaken, wireless chipsets slow down, firmware support ends. If you’ve tried everything reasonable and chronic disconnects persist on a router from 2018 or earlier, replacement is probably the answer. Reliable home routers in 2026 cost £80-£150 and last another half-decade.
For ISP-issued combination modem-routers that you can’t replace: ask the ISP to swap it. Most will if you explain you’re experiencing chronic disconnects despite multiple troubleshooting attempts. They’d rather send a new unit than schedule technician visits.
The investment of an hour of careful diagnosis (or a £100 router replacement) pays for itself quickly in not having to deal with daily disconnect frustration. Pick your fix based on what the diagnostic evidence actually points to, not whichever option is most convenient — replacing the router doesn’t help if the line outside has water in the conduit, and calling the ISP doesn’t help if your eight-year-old router is the problem. You might also run into Internet Connection Keeps Dropping.
