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’?


Question: Optimizing wireless router speed and minimizing interference
Answer: 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.