MacBook won't connect to internet

[AeroBar]

hi,

my desktop is working fine, but my mother's macbook won't connect to the internet. this has happened before.
what info do you guys need to help me?
in network diagnostics the internet and server are red, the rest are green.

cheers

 

[AeroBar]

hi,

the server is green now, but internet is still red.

why can one machine go online but another not?

 

[AeroBar]

\ok all six buttons went green but it went offline again