Please be advised that Roku Premier is only compatible with wireless b/g/n networks on the 2.4 GHz spectrum. Ensure that your router is broadcasting a 2.4GHz Wi-Fi network for the device to connect to.
You can also try configuring your router and use wireless channels 1, 6, or 11 which are the preferred channels in North America. Each time you change the wireless channel, you will likely need to apply/save changes before you are prompted to restart the router.
@RokuKariza-D The device has been working fine under the same network and router for almost a year now. I have restarted my router a couple times. All other devices are working fine and it’s just the roku that has suddenly decided to stop recognizing the wireless network. Do you think my Roku has a problem?