Your modem is working in bridging mode. I only realized that halfway through our conversation. The route magic
Code:
route add -net 10.0.0.138 -netmask 255.255.255.255 -interface 82.92.239.xx -cloning
route add default 10.0.0.138
from
http://readlist.com/lists/openbsd.org/misc/7/36639.html is the proper way to deal with a (A)DSL modem in bridging mode.
RE: default route
If you don't have a default route defined, the order should make no difference.
RE: changing local side of modem from 192.168.1.1/24 to 123.123.123.208/29
That would cost you a public IP address from your /29 pool.