It is likely a configuration with your network.
1. What are the Roku model numbers. (Setting/System/About for the current one). Second one you can determine from the box packaging.
2. What is the router model number. (look on sticker on bottom or side of router).
3. Who is ISP (internet service provider).
4. Are you using two (2) SSID? In other words, do you have the option to connect to either your 2.4ghz band or 5ghz band independently, or are you only seeing one (1) network name available to you for your network.
5. Are you sure you are entering the correct password for your SSID/network?
In order to switch off from your neighbor's internet in order to refresh your network, you can do a network connection reset from within Roku settings. Settings/System/Advanced System Settings/Network Connection Reset/Reset Connection.
Roku Community Streaming Expert
Just another Roku user... I am not a Roku employee.
Insignia RokuTV, Ultra 4660x, Premiere+ 3921, Express 4k+ 3941