I have the DPC3825 modem and I was having consistent lag spikes while playing video games and also the wireless connection was very poor. I did some reading and just decided that this was a below average router for me and so I went out and purchased a Linksys E8350 AC2400. I have Shaw Broadband 100 and the speeds were fine on my desktop with the speedtest. I got Shaw to put my modem into Bridged mode and set up my router. The wireless connection was instantly better throughout the house and I wasn't having lag spikes in my gaming anymore so I was super happy about that. The only problem I have having now is my download speeds are way too slow. With the modem -> router -> wired desktop I am getting about 30-40 Mbps from Speedtest.net when I was getting between 85-100 Mbps going through just the modem.
Basically connecting with just the modem my speeds were fine while wired but the wireless would cut out and be less than desirable. With the router everything performs almost perfectly just my download speed is WAY below where it should be and what I am paying for. I just don't have any problems otherwise so I can almost live with the low download speeds. I just know it should be better.
If you guys have any suggestion please let me know. I will try to provide you with as much information as possible.