A net is the emblem of St Peter (see Peter1) and St Andrew.
The Net is an informal term for the Internet.
in vain the net is spread in the sight of the bird proverbial saying, late 14th century, meaning that a person who has seen the process by which someone intends to harm them is unlikely to be in danger. The original allusion is biblical, to Proverbs 1:17, ‘Surely in vain the net is spread in the sight of any bird.’
slip (or fall) through the net escape from or be missed by something intended to catch or deal with one.
See also all is fish that comes to the net.