Samsung Galaxy 51 won't join my Wifi

[K8from8]

Ever since the an update last Saturday (1May) my mobile will not join my home Wi-Fi when I come home.  It did do it if I restarted it but now that no longer works.  Any ideas?  The Wi-Fi is working fine.

[Pugs1957]

Try rebooting your router.

[Debbie1986]

Disconnect from phone the start again that should short it out

[AndrewL]

@K8from8: Can you try heading to Settings > Connections > Wi-Fi > On > Tap the cog to the right of your router > Auto Reconnect > On > Back > Tap the 3 dots in the top right > Advanced > Turn on Wi-Fi Automatically > On. Does this resolve the issue? 

[K8from8]

Thanks everyone , I have tried all of the above.  It took turning the router off and on again to get it to join this time.  I tried restart several times.  It appears to be a problem if I have been out using 4G.  Any ideas?  I am sure it is linked to the new update.