What speed tier are you actually subscribed to ? With that knowledge you can decide. To simplify, lets say that if you have the Blast speed tier or anything faster you need to use a DOCSIS 3 capable modem. Anything slower than Blast you can use a DOCSIS 2 modem.
So since I have the Blast! speed tier I need a Docsys 3.0 modem? EG, I've seen you post similar info in the past; how do I get my modem upgraded to match my speed tier?
I have called Comcast Support three separate times in the last year and a half and asked for a Docsys 3.0 modem in order to support Blast!, only to be told that my current modem is fine and supports Blast. I currently have an Arris TM402P modem, which is ancient.
If Comcast won't allow me to upgrade to a Docsys 3.0 modem, am I expected to purchase my own and install it? Is that even permitted in my area? (SE PA)
Shame on them. They should practice what they preach and supply you with the recommended modem for your speed tier.. That said, you can purchase and use your own D3 capable straight modem anywhere in Comcast's footprint as long as it's not an eMTA/telephony type modem and is on their "Approved Modems List" here;
Even when I had an appointment set up to exchange the modem the tech refused to change it...So I called in and got a self install gateway device. Most people here, would not recommend a gateway device, but once the router part of the device is bridged, it's fine.
The problem is there are different speeds for Blast! in different markets...16/2, 20/2 which work ok with a D2 modem. If you get upgraded to 25/4 as I was, you will need a D3 modem to get the full benefit of it.
The other choice is buying an eMTA device from BestBuy with a Comcast Connection center. (since you have an Arris 402)
That shows I get 36/6 with powerboost, although it's actually provisioned at just over 26/4
When mine got upgraded I noticed the download speed was erratic, anything between 20 and 30 with powerboost using a D2 modem.
As soon as I connected the D3 modem, the download went to 36 with powerboost, and has remained pretty solid ever since.
As for buying an eMTA, up until now the only eMTA available for sale is the Arris TM722G Only available from BestBuy with a Comcast Connection Center or rep in the store, and this usually involves a paid tech install. The eMTA is about $150. Not all markets allow customer owned eMtA's.