Why does an address start with 169.254?

When an address starts with 169.254, check how the host identifies its local network, neighbours and route to other networks. IPv4 depends on the address, prefix length and gateway; IPv6 also depends on address scope and Neighbor Discovery. One wrong value can leave local communication working while breaking access beyond the subnet.

How to check the network settings

Start with the interface address, prefix, routing table and default gateway. Check whether the destination belongs to the local prefix and whether a default route exists. Do not change a mask or gateway by guesswork; compare it with DHCP or network documentation and repeat the same test after one controlled change.

The detail that matters

IPv4 169.254.0.0/16 is link-local space commonly selected when automatic configuration cannot obtain a normal address. It can support communication with compatible neighbours on the local link, but it does not provide a normal default Internet route and should trigger a DHCP/configuration check. For a calculation you can compare with the explanation above, use 2ip WHOIS/RDAP lookup.