From an address to a provider name
Your browser does not announce which company you pay. The page takes the public source address of your request, as described on What is my IP, and looks up who holds it. Address blocks are allocated by the regional internet registries to providers and large organisations, and a public geolocation service (ip-api.com) combines that registration data with routing data into the ISP, organisation, ASN and location fields shown here.
The lookup is skipped for private addresses, so on an internal deployment the page shows Unknown provider. On the public site, Unknown provider means the owner lookup failed or timed out. It does not mean the address is unassigned. Refresh and the second attempt usually succeeds.
Reading the connection type
The owner record carries three flags, and the pill shows whichever applies first: Mobile network when the block belongs to a cellular carrier, VPN / proxy when the address is known to front an anonymising service, and Data centre / hosting when the block belongs to a hosting or cloud provider. With none of the flags set, the page reads Broadband / ISP.
These flags are inferences from registration data, not measurements of your connection. A tethered laptop reads Mobile network because the carrier's block does. A small VPN provider that rents cloud servers reads Data centre / hosting rather than VPN / proxy. A home line on a provider that also sells hosting can occasionally be mislabelled. The ASN name is the more reliable field in that case.
Checking that a VPN or proxy is working
The simplest VPN test is to load this page with the tunnel off, note the ISP and ASN, connect, then click Refresh. A working VPN changes the provider to the VPN company or its hosting supplier, changes the ASN, and usually moves the location to the server's city. If the provider is still your home ISP, the tunnel is not carrying your browser traffic.
Look at both address rows in Connection details. The page detects your other-family address from the browser, so a VPN that tunnels IPv4 only leaves the IPv6 row showing your real address and provider. Corporate proxies behave the same way: the page names your employer or its carrier, because that is the network your request left from.
What the provider lookup cannot tell you
The page shows the last network your traffic left from, so it cannot see through a VPN, a corporate proxy or carrier-grade NAT to the subscriber behind it. Location is the registration location of the block, which for a mobile carrier can be a single city for the whole country. Nothing here identifies a person. Only the provider can map an address to an account.
The result is fetched fresh on each load and is not stored. If you need the owner of an address that is not your own, or want to share a result by link, IP lookup accepts any address and returns the same owner fields with the full record beneath them.