My ROKU device is slightly more than one year old and I have had excellent wireless connectivity to my Verizon FIOS router during this time. Recently in the NY metropolitan area we have experienced two power outages. Did not try ROKU until after the second power outage. Zippo-not able to connect via the wireless option. Went through steps to re-establish wireless connection and could not even get screen on ROKU which would allow me to do so. FIOS router with wireless was working fine. Did a factory reset and went through basic setup again. Three times after entering WEP and SSIP, the ROKU could not detect my network. After searching the ROKU forum came to realize others have had similar problem with re-establishing a wireless connection but a hardwired connection was always successful. It had been 30 minutes or so since the third try, and I gave a fourth try. Bingo! The ROKU found by wireless connection almost instantaneously.
Why it took four tries over a period of 45 minutes, I do not know. However, if you are in an area where power outages are possible, a hard wired connection appears to be recommended. Going through the factory reset process loses all you settings and you have to re-establish your ROKU account and NETFLIX account. This is a big PITA if you have forgotten your ROKU password, etc.