Upgrading Home Network

[Schwartzinator]

I have Comcast internet, phone, and cable and got fed up with the mediocre coverage offered by the Gateway 2-in one garbage they sent out. Internet speeds have decreased from ~170down to around 90-110 as well dropped connections and horrendous buffering times when streaming. I picked up an Asus-GTAC5300 whatever router and an Arris Surfboard 8200 modem and went to install them, but realized there's nowhere to connect the phone jack. I thought about using a splitter to send internet to the Arris, and phone service to the Gateway but wanted to check in with you fine people about any issues that may raise and how to actually do that.

 

[Alabalcho]

Gthus is not going to work. The moment you activate Arris your old gateway will die.
With a phone service, you don't have many options. Use your new router as an access point, and return the Arris.