Your problem may have been caused by an update to your router which affects some Roku models. If you receive this update it changes the router's wifi connection parameters for the 2.4 GHz wifi band from b/g/n to g/n. This has been reported for routers supplied by Comcast/Xfinity, Cox, and AT&T, but there may be others.
Affected users report the Roku identifies the local network as available and rates the connection quality, but will not then connect. The fix is to switch the router configuration protocols from the g/n wifi set by the update back to b/g/n. If you don't have access to your router's configuration controls you may have to have your internet provider do it for you.
Step-by-step post from AvsGunnar for Comcast/Xfinity users:
https://community.roku.com/t5/Network-Wireless-Wired-Connections/Error-014-30-stuck-for-three-days/m-p/749194/highlight/true#M21388
