IPv4 link-local (``169.254.x.x``) gateway does not function
On 2.5.1, there is a regression caused by the change in #11713 which ends up treating IPv4 link local addresses like IPv6. It incorrectly attempts to add a
% scope to the address and fails, since it doesn't exist for IPv4. Due to that incorrect usage, if an IPv4 link uses a link-local address from 169.254.x.x as its gateway, the route is not added to the table.
Limiting the change from #11713 to only IPv6 addresses partially solves the problem but also results in "route has not been found" errors similar to those reported in #11713, so that change alone is not sufficient to solve the problem.
See https://forum.netgate.com/topic/162935/pfsense-2-5-1-not-recognizing-my-default-ipv4-route for additional details.