I´ve had several problems when changing ip, and such, using scoadmin.
Try to manually change the settings using ifconfig AND run a text-editor on /etc/rc2.d/S85tcp to make the same changes there. The section where you should enter the information is...
#
# Interface configuration -- edit as appropriate.
#
you should add the default route here (/etc/rc2.d/S85tcp) as well.
you should look into the manual pages for ifconfig but here´s some examples...
ifconfig lo0 127.0.0.1 perf 57344 57344 1
sets the localhost ip
ifconfig -p net0 192.168.0.1 netmask 255.255.255.0 broadcast 192.168.0.255 perf 24576 24576 1
sets ip of first NIC.
/etc/route add 0.0.0.0 192.168.0.254 1
routes traffic to ip 192.168.0.254 /Sören