About which channel to use, the book "Wireless network coexistence" by Robert Morrow has this to say:


  In north America, a non-overlapping
  set consisting of channels 1,6, and 11
  or an overlapping set composed of
  channels 1, 3 5. 7, 9, and 11, can be
  selected. The corresponding sets in
  Europe are channels 1, 3, 5, 7, 9, and
  11, can be selected.


To detect interference, you might use a WiFi finder to map out your environment.
This article discusses several such utilities.

Optimizing wireless router speed and minimizing interference

  He turned back to Harry. "You'll soon find out some wizarding families
  are much better than others, Potter. You don't want to go making
  friends with the wrong sort. I can help you there."   He held
  out his hand to shake Harry's, but Harry didn't take it.   "I
  think I can tell who the wrong sort are for myself, thanks," he said
  coolly.  (Harry Potter and the Sorcerer's Stone)


Is ‘there’ a deictic indicating Hogwarts school where they’re going now, or does it have an adverbial meaning ‘at that point’?
