← All guides: Why is my WiFi slow?
You tap a link and nothing happens. A second, sometimes two, of complete blankness - then the page snaps in all at once and everything is fast again. It's worst on sites you haven't visited recently, and video that's already playing is unaffected. Speed tests, naturally, look perfect.
That specific shape of slowness - a delay before loading rather than during it - usually means slow DNS.
DNS is the internet's phone book. Websites live at numeric addresses, but you type names, so before your phone can fetch anything it has to ask a DNS server "what number is this name?" and wait for the answer. Only then does the real connection begin.
That lookup should be almost instant: 20 to 50 ms is healthy, and anything over 100 ms is slow enough to feel. A single slow lookup wouldn't matter much, but a modern web page pulls in fonts, images, analytics and scripts from a dozen different domains, each needing its own lookup. Multiply a 200 ms delay across all of them and the page feels sluggish no matter how fast your connection is.
Unless you've changed it, you're using whatever DNS server your internet provider handed out. Some ISPs run excellent ones. Plenty run servers that are overloaded at peak times, physically distant, or busy doing extra work - filtering, logging, or redirecting mistyped addresses to a search page full of adverts. Any of that adds delay to every single lookup you make.
Compare your current DNS against a known-fast public one. Look up a handful of domains through each and compare the average response time. If your provider's server averages 150 ms while a public server on the same connection averages 20 ms, you've found your problem - and because both tests run over the same WiFi and the same line, it's a fair comparison that rules out everything else.
Android has this built in. Go to Settings → Network & internet → Private DNS, choose "Private DNS provider hostname", and enter one of:
one.one.one.one - Cloudflare, generally the fastest, and states it does not log your browsingdns.google - Google Public DNS, very reliable and well distributeddns.quad9.net - Quad9, slightly slower but blocks known malicious domainsThis has a second benefit worth knowing about: Private DNS encrypts your lookups. By default, every domain you visit is sent in the clear, so whoever runs the network can see the name of every site you go to even when the sites themselves use HTTPS. Private DNS closes that gap.
Setting DNS in the router means every phone, laptop, console and smart TV in the house gets it without individual configuration. Open your router settings, find the DNS fields - usually under Internet, WAN, or DHCP settings - and replace the automatic entries with 1.1.1.1 and 1.0.0.1 (Cloudflare) or 8.8.8.8 and 8.8.4.4 (Google). Reboot, and everything on the network picks up the change.
192.168.1.1 (or 192.168.0.1) into your browser while on WiFi. The admin password is usually on a sticker on the router itself.
Changing DNS does nothing for download speed, video quality, or the responsiveness of a game - it only removes the pause at the start of each connection to a new site. If pages start instantly but then load slowly, look elsewhere: bufferbloat if it's worst during downloads, channel congestion if it's worst in the evening, or weak signal if it's worst in one room. It also won't help if your ISP blocks certain sites at a level deeper than DNS.
Related: WiFi lags when downloading? That's bufferbloat · Is my home WiFi secure?