This sounds like a matter of finding the connected components of a graph. Particularly if signal strength doesn't matter except as a boolean.

Something somewhat like this:

my @networks = ();
for my $device (@deviceList)
{
  if (not defined $device->{network})
  {
    $_->{network} = $numDisjointNetworks for BFSonConnections($device)
+;  #DFS works fine too
    $numDisjointNetworks++;
  }
  push @{$networks[$device->{network}]}, $device;
}
[download]

should give you a LoL of networks and devices in them, and each device will know which network it is in.