Do not use a hidden SSID - it really does nothing to improve security! Some Chromebooks will have problems connecting to a hidden SSID.Disable IPv6 - unless you are specifically using it.Do not select WPA only, as it is not secure. In the router's WiFi security settings, make sure that your encryption is set to WPA2-PSK with AES Encryption.Having two active routers can cause all sorts of problems. Contact your ISP if you need help with that. If you have your own WiFi router, and have plugged it into the router provided by your internet service provider (ISP), you should change the ISP's router to 'bridge mode'.If you are using an extender or repeater, turn it off to see if it is contributing to your problems.Your Chromebook may try to connect to the 5 GHz band, and then have problems reconnecting in a weaker signal area of your home. 5GHz does not travel through walls and floors well.

This will let you choose the band and see if one works better than the other for your location in your house. If your router is dual-band (2.4 and 5 GHz), assign a different SSID to each band.A firmware update in the router can sometimes fix compatibility issues.If you have access to your router's settings, these tweaks often solve the problem:

Err connection refused chrome