Sudden internet slowness is almost always something new competing for the same connection, not a change your ISP made. A download, an extra device, a weak Wi-Fi signal or a VPN can all do it, and each one shows a different pattern once you know what to look for.
"My internet is slow" gets treated as one problem with one fix, usually a call to the ISP and a long hold. Most of the time it isn't the ISP at all - it's something that started recently on your own network, and it stops as soon as that thing stops.
This page skips the generic "restart everything" list and goes at the decision: how to tell what actually changed, and which of the handful of usual causes it is before you spend twenty minutes on hold for a problem a restart would have fixed.
What Actually Changed?
Internet connections do not get slower on their own. Something is either using more of the connection than before, or something between your device and the wider internet is adding delay it was not adding yesterday. The question worth asking is not "why is my internet slow" but "what started around the time it got slow" - a backup, a new device on the Wi-Fi, an update downloading in the background, a VPN switched on, or nothing on your end at all.
Two things narrow this down fast. Whether it is slow on every device or just one, and whether it is slow all day or only at certain times. Those two answers point almost directly at which section below applies to you.
Is the Problem Local or on Your ISP's Side?
Everything between your device and your router is yours to fix. Everything past your router - the line into your building, the ISP's network, the site you are trying to reach - is not, and no amount of restarting your own equipment reaches it.
Each step you can rule out on your own; what's left after the third one is theirs to fix.
What Are the Most Common Causes?
| Cause | What It Looks Like | Quick Check |
|---|---|---|
| Heavy background use | Slows during a backup, update or someone else's stream | Pause it and re-test |
| Weak Wi-Fi signal | Fast on Ethernet, slow on Wi-Fi in one room | Move closer or switch to Ethernet |
| Peak-hour congestion | Slow at the same time each evening, fine late at night | Compare a speed test at 2am and 8pm |
| Router needs a restart | Gets worse gradually over several days | Power-cycle it and re-test |
| VPN overhead | Slow only while connected to a VPN | Re-test with the VPN off |
| ISP-side issue | Slow on every device, every room, all day | Compare the result to your plan's advertised speed |
Could Too Many Devices Be Slowing You Down?
A home connection is shared, and it is easy to lose track of everything drawing on it at once. The usual suspects are rarely the device you are actively using.
- Cloud backups. Phones and laptops often back up photos the moment they join Wi-Fi, silently, in the background.
- Automatic updates. Game consoles, computers and phones can all pull large updates without asking first.
- Someone else on the network. A second person streaming in 4K or downloading a large file uses real bandwidth, even in another room.
- Smart-home devices. Cameras that upload video continuously are a common, overlooked drain.
Could Your ISP or Your VPN Be the Reason?
Two different things get blamed on "the ISP," and they call for different responses. Congestion is the network being busiest at the hours everyone is home, which eases off later at night and is not a fault to report. Throttling is an ISP deliberately slowing certain kinds of traffic, such as video or file-sharing, which behaves differently: it is selective rather than constant, and it is the one case where turning a VPN on can genuinely help, because encrypted VPN traffic is harder for an ISP to identify and slow down.
A VPN can just as easily be the cause instead of the fix. Encrypting every packet and routing it through a distant or crowded server adds delay that was not there before, and a server on the other side of the world will always feel slower than a nearby one. If your connection is only slow while the VPN is on, that is a straightforward answer, not a mystery - how to check if your VPN is actually working covers testing it properly, including whether it is doing anything more than adding delay.
What Does a Speed Test Actually Tell You?
A single speed test tells you what your connection could do at that exact moment, on that exact device, competing with whatever else was running at the time - not a permanent number. What actually helps is a reading with a timestamp, taken more than once: once while whatever you suspect is running, and once after it stops or at a different hour.
The Internet Speed Test tool gives that reading in a couple of minutes, with the date attached so you have something to compare later. If the number looks fine but pages still feel slow to load, latency matters more than raw speed, and the Ping Tool shows that directly. And if only some sites are slow to start loading while others are fine, the delay is often in name resolution rather than the connection itself, which the DNS Lookup tool can confirm.
What to Try Before You Call Your ISP
- Pause any obvious downloads, backups or streams and re-test.
- Switch to Ethernet, or move closer to the router, to rule out Wi-Fi.
- Power-cycle the router and modem, and give it a minute to fully reconnect.
- Turn the VPN off, re-test, then turn it back on and re-test again.
- Run a speed test at a quiet hour and compare it to one from the slow period.
- If every check still points outward, call with both readings in hand - it is a shorter call than starting from "it feels slow."
Frequently Asked Questions
Why is my internet slow only at night?
This is usually congestion, not a fault. Everyone in your area is online at the same hours, and the shared part of the network gets busiest exactly then. It normally clears up late at night or early morning, which is a useful comparison to make with a speed test.
Does restarting my router actually fix anything?
Often, yes. Routers accumulate small memory and connection issues the longer they stay on, and a slowdown that has been getting gradually worse over several days is the classic sign of it. A full power-cycle, not just turning the Wi-Fi off and on, clears that state.
How can I tell if it's my Wi-Fi or my ISP?
Run the same speed test over Ethernet and over Wi-Fi. If Ethernet is fast and Wi-Fi is slow, the problem is local - signal strength, interference or distance from the router. If both are slow at the same time, the cause is more likely further out, on your ISP's side.
Is a VPN supposed to make my internet slower?
Some slowdown is normal, because encrypting traffic and routing it through another server both add a little delay. A large or sudden slowdown usually means a distant or crowded server rather than the VPN itself being at fault - trying a closer server is the first thing to test.
Why is my speed test lower than my plan's advertised speed?
Advertised speed is a maximum under ideal conditions, not a guarantee at every moment. Wi-Fi overhead, other devices on the network, the time of day and the distance to the test server can all bring a single reading below that number without anything being wrong.
How long should I wait before calling my ISP?
Once you have ruled out background usage, Wi-Fi, a router restart and a VPN, and the slowdown is still there on every device at every hour, there is nothing left to test from your side. Calling with a couple of dated speed test readings in hand at that point is a shorter conversation than starting from scratch.
Final words. A sudden slowdown almost always has a specific, recent cause rather than being a permanent change to your connection. Work through what's local first - devices, Wi-Fi, the router, a VPN - and only treat it as an ISP problem once every one of those has been ruled out with an actual test. You can run that test any time on the MyIPShow homepage.