I have a Samsung GT-S5620 unlocked GMS phone that used to work on my WiFi in house. Lately, I keep getting a no response from ap message when I try to connect. My laptop and iPad work on the WiFi with no problems. What can I do to fix this?
Usually this is either because of wrong security settings or MAC filtering.
Go to your Routers or Access Points web interface and make sure you are using the correct security and encryption settings and if activated check that your mobile phone is allowed within the MAC filter.
If you confirmed the settings and still can't connect you could try changing through the encryption settings (TKIP, AES, TKIP+AES). Another option is changing the security mode but this shouldn't be a problem when using either WPA or WPA2.
Also if the option is available try connection your phone to another (known or public) WiFi network to make sure the problem is not on the devices end.