DPC3825 w/e2500 router only getting 25-30Mbps with Ultimate Package

The DPC3825 is a gateway, which means it includes a router.  You have that connected to a Linksys e2500?  Are you bypassing the router internal to the 3825?  Having a router connected to another router in a nono.

what level of service do you have?  The 3825 is 8/4 channels, approved up to Premier level only.  Also, the e2500 is an N300 router with 100Mbps Ethernet ports.  That won't even give you Premier speeds, it's almost usable at Preferred and below.

if you are on Ultimate, neither device will support those 300Mbps rates.  More details about your network, please.

I have the Ultimate package. So I'm assuming I need a new modem rated for Ultimate speeds? If so, I'll just be buying my own.

I also have the wireless interface on the modem turned off because it was constantly telling me that I had "limited connectivity" and I had a router in storage. Was told to turn the wireless interface off and use the router.

Do you have dhcp turned off too?  If you have the routers wan port connected to the gateways lan port are they both doing NAT?  Have you set the gateway into bridge mode, if that is even possible?  You can't just turn off wireless and use a gateway with a router, that wasn't good advice.

For the future, the router is the weakest link.  As I said, it has 100Mbps Ethernet ports, the best you can expect is 100 out of the 300Mbps you pay for with it in the network.  It should be replaced with a gigabit router preferably supporting wireless ac. Also, you want a modem with at least 16 channels down.  As far a buy or rent, your preference, makes no difference to me.  I'm just a customer like you, trying to help out.  

Turning off wireless does make a gateway act as a modem. It still acts as a wired router to your router. Having two routers in line slows your performance down. Some routers do it better then others, but its like driving with the brake on, its better to just not. Bridging turns unplugs the brain in the gateway, directing all traffic directly to your router, which is what you need, I just don't think that gateway offers it.  You could turn your router into a AP or swap the gateway for a modem. 

Hi BrentP,

Your current equipment setup could be causing the slow speeds that you're receiving. What have your speed results been lately? Have you run a wired test to the modem? The upload and download speeds of the Ultimate Tier have recently been increased in your area. To experience the new speeds, a DOCSIS 3.0 (16x4) device is needed. Modem exchange is free for current Ultimate Tier customers who are renting the modem.

So I can upgrade for free? I was going to purchase the SB6183 modem, but I see that it seems to be the one offered from Cox for Ultimate tier. Do I bring in my DPC3825 to my local Cox and just swap them out? 

BrentP said:

So I can upgrade for free? I was going to purchase the SB6183 modem, but I see that it seems to be the one offered from Cox for Ultimate tier. Do I bring in my DPC3825 to my local Cox and just swap them out? 

If you are renting your gateway from Cox, upgrades are included in the rental service so yes, you can upgrade for free.

Remember, the SB6183 is a modem only, not a gateway.  You need to replace your router too, the e2500 will not support anywhere near Ultimate speeds.  If you want to stick with a gateway, Cox offers the Netgear C6300 supporting Ultimate.

Yea, I was planning on getting the SB6183 and TP-LINK Archer C9. 

I've picked up the SB6183 and a suitable router. Have everything up and configured and attached with a Cat 5e cable directly and only have 62 down. Is there something Cox needs to do on their end with the new modem?

I will do that this morning when I get off. My laptop, which is the only way I can directly connect, runs on Linux Mint, but has recovery mode with networking. In normal boot mode and connect by cable I'm getting the 62. My PC on WiFi was getting ~55 down. I'll report back when I try a speed test again in safe mode.