Why Is My Internet So Slow Suddenly? (12 Causes & Fixes)
When internet that worked fine yesterday suddenly crawls today, the cause is usually one of these twelve. Work through them top to bottom.
Quick things to check first
- Reboot your modem and router — fixes a surprising number of sudden slowdowns.
- A background download or update hogging bandwidth (game updates, cloud sync, phone backups).
- Too many devices active at once.
- Peak-hour congestion — slow only in the evening points to this.
- WiFi interference from a new device or neighbour's network.
If those don't fix it
- A device caught in a loop — re-downloading or uploading something large.
- Malware on a device using bandwidth in the background.
- Overheating router — feel if it's hot; give it ventilation.
- Packet loss on the line — check it in our test; consistent loss means a line issue.
- ISP outage or throttling — check our outage checker and test at different times.
- A failing cable — loose or damaged coax/fibre/Ethernet.
- You hit a data cap — some ISPs throttle after a monthly limit.
Key takeaway: Run a speed test first. If wired speed is normal but WiFi is slow, it's your WiFi. If wired is also slow with packet loss, it's the line or ISP.
Diagnose it in 30 seconds
Run our test and look at three things: is the speed far below your plan, is there packet loss, and is the bufferbloat grade bad? Those three answers point you straight to the cause.
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