Most modems only have 1 Ethernet output, don't be a bitch about it and do it manually.
they all have only 1.
to share a ip address, software would be required (a router)
or a combined modem/router that all dsl and some cable ISP just give you.
for the record, i cannot stand the combined units. i always have requested JUST the cable modem. as nothing beats having your own real router.
i hate ISP software.
or of course, the option to go single hardwired like OP is trying.
couldnt a person using a combined box just adjust his modem/router into a simple modem? basically the bridging settings without a bridge? lol