Drilling into top plate for ethernet

Hi - I am trying to run ethernet from my attic, down the wall, and into a keystone jack. I did some measurements and started to drill a hole in the top plate where I calculated would be in between 2 studs. I used a regular 3/4" spade bit but as I drilled i kept hitting wood as far as my drill bit would go.

1) How deep should I have to drill into the top plate before I get into the wall cavity?

I have a much longer flex bit I can use but before I drill further I wanted to ask about the depth. Im not sure if I just need to drill a bit further or if I've miscalculated and am just drilling down vertically into the stud.

 

If there is a drywall nailer on top of your top plate it's possible the wood could be 4 1/2" thick. If you were drilling into the end of a stud you'd probably be hitting nails.

 

Thanks XSleeper. I think you were right. I used my 4 ft long 3/8" flex bit and only needed to drill down another 1/4" or so and I was in the wall. Used my boroscope and while the wall has some light insulation I could get down to the floor so I should be able to make this work. I appreciate your info.