my iphone 6 keeps on disocnnecting from the wifi connection

my I phone 6 is disconnected from the wifi connection & when I tried to reconnect it keeps on telling me the password is wrong although its not .

I forgot the wifi connection that was saved & restart my phone but nothing worked

& today I reset all the network settings & I tried more time it worked but a couple of hours & it had been disconnected one more time & still having the same problem !