Router
Router
For a wired link when a device lacks wifi support, consider connecting an Android or iOS phone via Wi-Fi and then using USB tethering—though I’m not entirely sure about Android’s capability. If you require a true Ethernet connection, a laptop works well; in Windows it’s called ICS, and you can locate it in adapter settings. You might also use bridging adapters on Windows.
It seems odd, as it appears they’re suggesting you change your service provider.
Ah, righto, in that case, that does suck. You could get a router capable of acting like a wireless bridge. This would "suck in" wireless coming from the modem they' ve given you, then output it over 4 wired ethernet jacks.