Just bought a roku, can’t connect to Wi-Fi

Lunsmann1-

There are some router setting issues that can prevent establishing Roku WiFi connections. And to make matters worse, some of them can be set by recently-reported router updates. These have primarily been reported with routers supplied by internet providers (Comcast/Xfinity, Cox, and AT&T so far), but it's possible they could also occur with other internet providers or user-owned routers that have received similar updates.

Your symptoms sound like this one:

• ROKU LOCATES NETWORK AND REPORTS NETWORK QUALITY BUT CANNOT CONNECT
  Some router updates have changed the router's connection settings on the 2.4 GHz WiFi band from b/g/n to just g/n, causing Rokus connecting to the 2.4 GHz wifi band to lose their ability to connect to the network.
  
  Note that, of recent Roku models, non-4K Roku Express/Express+ (model numbers below 3940) and Premiere/Premiere+ (model numbers below 4620) can ONLY receive the 2.4 GHz band and are therefore affected by this.  Other models which are capable of also using the 5 GHz WiFi band may still attempt to connect to the 2.4 GHz bans and be similarly affected.
  
  The solution is to set the router's configuration back to using b/g/n. 

Reconfiguring Router
Thanks to forum user AvsGunnar  for providing the links below to instructions for reconfiguring router settings for the listed internet suppliers. If you can't do this yourself, you may need to contact your internet provider to make these changes for you:

• Xfinity / Comcast → ( https://www.xfinity.com/support/articles/change-wifi-mode-admin-tool-xfinity-xfi ) with a walkthrough ( https://community.roku.com/t5/Network-Wireless-Wired-Connections/Error-014-30-stuck-for-three-days/m-p/749057#M21380)
  
  
• Cox → (https://www.cox.com/residential/support/managing-your-in-home-network-with-my-wifi.html)
  
  
• AT&T → (https://www.att.com/support/article/u-verse-high-speed-internet/KM1046172). You can select your appropriate router from the drop down menu.

If your problem was not caused by any of the above, a restart of the router (even if other devices are still connecting) followed by a restart of the Roku may allow the connection to be reestablished. Depending on your Roku model you'll find the "System restart" option under either "Settings > System > Power" or if you have no "Power" option, under "Settings > System", or if more convenient you can just pull the Roku's power for a few seconds and let it restart.