Time Out Issues

I've been having problems with timing out. Im playing Nazi Zombies, over an hour into the match, and I Time out. When I get back to the menu, it tells me

'No network connection detected.
You must have an active network to play online'

I don't get signed out, nothing is done to the router, the laptop was not in use, no other playstations in or around my house, and yet, I time out.

Now, this doesnt always happen, but when it does it is really aggravating. I was on round 40 and I timed out. I read somewhere that I had to change my MTU, and I did, and I still time out. I have a wireless connection, and no ethernet cable or it would be wired. Is there any way to fix this without having to go get the cord?

Sounds like you are suffering from signal loss.
This can happen alot with wireless devices, especially if there is a stronger signal being put out by another device in the area.
You can try setting your router to a different channel and see if that works.