I previously had a dedicated modem provided by Comcast (Arris TP402P)
Are you sure that is the model number of the modem? It's not listed as an approved device for Comcast. An internet search returned no results for that model. There is an Arris TM402P, which was end of life as of June 2013. Is the reason you got a new modem because the other one was end of life?
Go back to a regular modem and get rid of the gateway unit. One of the problems with the gateways is that Comcast will use it as an Xfinity hotspot. This means that other Xfinity customers can use that hotspot to connect to the internet. The hotspot function can be disabled but if I recall correctly some people have reported it somehow gets re-enabled. More information on that here http://arstechnica.com/information-technology/2013/06/comcast-turns-your-xfinity-modem-into-public-wi-fi-hotspot/
The article states that it's available only in certain areas. It may have expanded since it was written if you are not in one of the listed areas.
And in the Comcast help forum
What I don't know is whether putting a gateway into bridge mode will disable the hot spot. Since it is a separate signal I *think* it will not.
If you want to keep the gateway device I have a suggestion for troubleshooting your issue.
Post in the Comcast Help Forums.
Those Forums are provided to Comcast customers, and are a great resource for vendor specific issues. There are Forums for computer issues, email issues, security, internet, cable tv, CDV, billing, and customer service.
Many times we, the users there, can provide answers tech support and customer service can't.
Click the link below. The forum landing page will open. Click Sign In. Log in with your Comcast user ID (the part before .net) and your password. You will next see a first time forum users page, asking you to choose a screen name for use in the Forums. Once you set that up, you'll be taken back to the landing page. PLEASE DO NOT USE YOUR COMCAST EMAIL NAME FOR YOUR FORUM USER NAME.
Before posting, take a moment to read the Posting Guidelines. The link is on the top right hand side of the page.
Then choose the appropriate board to post in. In your case post in Home Networking / Router / & WiFi Gateway Help
Hopefully someone will be able to help you.
One thing to be aware of: By default you will be notified via email every time someone replies to a topic you have started or replied in. If you do not wish to receive the notifications you can disable them by clicking My Settings/Subscriptions & Bookmarks tab. Uncheck the box next to Automatically subscribe me to topics I participate in. Scroll down and click Save.
DO NOT USE THE UNSUBSCRIBE LINK IN THE REPLY NOTIFICATION EMAIL. Due to a quirk with Lithium, the forum provider, if you use the link it severs the connection between your forum user name and the email address you sign in with.
Result: your forum account no longer exists in the database and it tells you that you are banned.
(Once you get to the forum, save the page to your favorites/bookmarks. If you want to get to it from the Comcast home page, you have to jump through hoops to reach it)
Edited by Queen-Evie, 13 September 2014 - 07:17 PM.