Why does my LG 3S drop my home WIFI after 3 seconds?

A

AC Question

I have an LG 3S that drops my home wifi connection after 3 seconds.
It has been doing this for about 7 days now.
I have a stable connection to Wifi at work on the same phone.
I have re-booted my router a few times without success.
I have disconnected and re-connected my phone to router but nothing but the connection only ever last a few seconds before dropping out.

Please help...