Broadband keeps dropping and losing connections

[IanG3]

Having an issue with my WiFi constantly dropping today and some devices not being able to connect 

the router has 3 lights and I have tried rebooting it multiple times 

the sky checker says everything is fine but clearly it's not

some devices still connect, some connect for a while then drop, some say they're connected but they're not, and some now won't connect at all

all were working fine yesterday 

help!