Why do my iPhone wireless network apper on my mac?

Hi there,

Have a 2012 iMac now running Yosemite, and for a while it has been dropping wireless network when waking from sleep.

Think I have pinpointed the issue to the fact my mac absorbed all the wireless networks I have visited on my iPhone, and is stuggling to find the right one when waking.

I clear them out via system preferences, network connections, advance, this helps the issue for a while but then soon fills up again with new connections.

How is this happening and how can I prevent it?

Many thanks in advance,

Christopher