Why a site works on mobile data but not on Wi-Fi
A focused way to distinguish DNS, router, browser and network-policy failures.
If the same device can open a site on mobile data but not Wi-Fi, the website is probably available and the difference is somewhere on the Wi-Fi path.
Confirm the comparison
Use the same device, browser and URL, including the https:// scheme. Turn Wi-Fi off, test once, then turn it back on and repeat. Avoid comparing two devices because their DNS cache and security software may differ.
Check name resolution
Compare the resolved address on both connections. A stale router cache, filtered resolver or incorrect local override can return a different result. Flush only the device cache first; rebooting every network device destroys useful evidence.
Test another browser and a private window
This distinguishes browser state and extensions from the network. If every browser fails only on Wi-Fi, inspect router filtering, parental controls, VPN routes and corporate policy.
Look for IPv4 and IPv6 differences
One network may prefer IPv6 while the other uses IPv4. Test both paths before disabling either protocol permanently. A correct fix repairs the failing path rather than hiding it.
When you manage the website
Check edge and firewall logs for the Wi-Fi public address. Rate limits and reputation filters can affect one network while leaving mobile users untouched.