Any 486+, old Mac, old Sparc box can be used, one doesn't need a Soekris or similar WRAP platform. In my case, the "home" router is an OpenBSD/i386 platform that also provides a number of additional network services.
There's been lots of discussion, here, of the advanced network capabilities of the *BSDs over any SOHO router. In the case of OpenBSD, that includes the extremely capable
PF (which has been ported to FreeBSD), as well as features such as
carp(4),
ifstated(8),
pfsync(4),
relayd(8) ... the list is endless.