I assume you will be hooking up a PC too?
If so you would need a router (wireless or wired depending if you are able to run ethernet cable to the HR20).
If you are able to run a ethernet cable than you would just run an ethernet cable from the modem to the router and than one line from the router to the PC and another one from the router to the HR20.
If you cannot run a line from the router than you would need a wireless router and wireless adapter with an ethernet connection, not USB. Any unit would work but you may want to check the CE forum and take a look at the thread about the Linksys WGA600N.
If so you would need a router (wireless or wired depending if you are able to run ethernet cable to the HR20).
If you are able to run a ethernet cable than you would just run an ethernet cable from the modem to the router and than one line from the router to the PC and another one from the router to the HR20.
If you cannot run a line from the router than you would need a wireless router and wireless adapter with an ethernet connection, not USB. Any unit would work but you may want to check the CE forum and take a look at the thread about the Linksys WGA600N.