Why is my internet slow at night?

If your connection is fine in the morning and crawls at 8 pm, you’re not imagining it. The usual cause is that everyone around you is online at the same time. Here’s how to work out which part is slow, and what you can do about it.

1. Network congestion (most common)

Home internet is shared. Your ISP sizes its network for typical demand, not for everyone at once. Between roughly 7 pm and 11 pm, when people stream, game and download, the busiest parts of the network (the local node, the ISP’s backhaul, or links to other networks) can fill up. Fibre suffers less than LTE, 5G, cable or ADSL, but it isn’t immune.

How to tell: run the speed test on a cable at 10 am and again at 9 pm, several days in a row. If speed drops and ping rises only in the evening, and only on your connection, the ISP is congested.

2. Wi‑Fi interference

Your neighbours’ Wi‑Fi is busy in the evening too. On the 2.4 GHz band, nearby networks overlap and slow each other down. Fixes: use 5 GHz (or 6 GHz) when you’re close to the router, move the router up and away from walls and the microwave, or use a mesh system or cable for TVs and consoles.

3. Your own household

Evenings are when your own family streams in 4K, games update and phones back up photos. Check the router’s device list or traffic stats. Some routers have QoS settings that prioritise calls and games.

4. Fair-use policies and throttling

Some plans, especially uncapped LTE and 5G, slow you down after a certain amount of data or during peak hours. Read your plan’s fair-use policy. A VPN test can help: if speeds improve a lot with a VPN at night, your ISP may be managing certain types of traffic.

5. Busy servers and routes

Sometimes it’s the other end. A game server or streaming service can be overloaded, or the route to another country can be congested. If one site is slow but the speed test is fine, the problem is probably the route to that site.

6. Shared IP (CGNAT)

Many mobile and some fibre ISPs put customers behind CGNAT, so hundreds of people share one public IP. It doesn’t usually lower speed, but it can cause captchas, blocks and strict NAT in games during busy periods.

What to send your ISP

Keep a short log: date, time, wired or Wi‑Fi, download, upload and ping. Include your public IP and ISP name. Evidence of an evening-only drop on a cable is hard to argue with.

Frequently asked questions

Why does my internet slow down every evening?

Usually network congestion: more people online between about 7 pm and 11 pm fill shared parts of the ISP network. Wi-Fi interference and your own household use add to it.

How can I prove my ISP is slow at night?

Run a wired speed test in the morning and in the evening on several days and log the results with times. Share the log with your ISP.

Will a VPN make my internet faster at night?

Usually not, because it adds overhead. It only helps if your ISP throttles certain traffic or has a congested route to a particular service.