Streaming from MacBook Air to Apple TV via Airplay mirroring causes stuttering

Question

So... I'm trying to stream video from Safari on my Mac to my Apple TV via Airplay mirroring. Most of the time, the video starts off just fine, but after a while, it begins to stutter and lag on my Apple TV. The video is playing just fine on my Mac, but as it's mirrored over to the Apple TV, it begins to stutter and lag on the Apple TV only; not on my Mac. I then quit out of Safari, turn off wifi on my Mac, restart the Apple TV and restart my Time Capsule. Once I do that, it works fine, intermittently for a bit, and then starts to give out again.
I have a 2013 13" MacBook Air with 8 GB's of RAM, an Apple TV 2 and 3, a previous generation Time Capsule (802.11n), and 50 Mbps wifi from AT&T Uverse.
What gives? What am I doing wrong? Shouldn't this stream just fine under these circumstances?
Thanks for any help you can provide.
P.

Answer 1

Hey vazandrew,
Thanks for the update on the encryption piece. I didn't know that. I thought you meant something like using a VPN.
And yeah, 4 years is a while. I just figured if the drive was still humming along all should be well. I didn't think that performance could be affected in this way just from using an old router.
The issue does occur on both Apple TV's. Near the Apple TV's are just my TV sets. One ATV also has speakers nearby it. The ATV's are not sitting inside of a closed space. They're on top of the entertainment unit. The rest of the appliances are below and inside the unit.
Near the Time Capsule is the Uverse Gateway modem for my cable tv, a Motorola SB6141 modem for my internet with Atlantic Broadband (I mistakenly mentioned initially that my internet was with Uverse), an APC battery backup, my HP printer, a USB hub, a power strip, and a couple of unplugged external hard drives.
Thank you again.