Need help matching modem to router

ftngrave

Junior Member
Dec 19, 2017
2
0
1
Sorry for the long post but I would be forever grateful to anyone who can help me understand modems and how to choose the right one, to match a router's specs.

So I moved into a new house and decided I'd upgrade for the first time to a 100 mbps download speed internet plan (10 mbps upload) from Cox. Not really knowing much about internet, and after hours of research, I decided
to buy a Trendnet AC2600 TEW-827DRU router for $110. It's dual-band: 800 mbps advertised speed on its 2.4 GHz band, and 1733 mbps advertised speed on its 5 GHz band. According to pcmag.com, they tested actual speeds on its 2.4 band at 108 mbps in the same room and 75.3 mbps at 30 feet. On the 5 GHz band, they tested actual speeds at 590 mbps in the same room and 260 mbps at 30 feet. My goal was to choose a router that will get me as close as possible to 100 mbps speeds on both bands for several devices throughout my 2 story house (while taking price into consideration).

I had assumed that matching a modem to a router would be simple. I thought it just needed to have a gigabit port, be dual band 802.11 AC, DOCSIS 3.0 or higher, and certified by Cox. After choosing my router, I discovered that Cox has a "Cox Certified Modems List (with actual modem models listed)." There are also modems on Newegg that state they are Cox compatible but are not on this list. After looking at these modems, I've become confused again and have some questions.

I don't want the modem to bottleneck the throughput wireless speeds of the Trendnet AC2600 router. I learned modems have bonded channels, for instance 8x4, which translates into 344 mbps download speed and 172 upload speed. Are these 8x4 speeds theoretical or actual? Is a 8x4 modem not going to bottleneck the speeds I can get (like close to the speeds as tested by pcmag) with the Trendnet AC2600 router? Or do I need a higher channel count like 16x4?

A few of the modems on newegg have AC numbers or list that they're dual band capable. I thought the router is what handles being simulatenously dual band. Does one's modem also have to be dual band (if so, I don't know how to tell if a lot of modems are dual band as their specs don't say)? Why do a few of the modems have AC numbers (a lot of them don't)? Is this relevant? Like will an AC1600 modem bottleneck my Trendnet AC2600 router?

For instance, the Arris SBG6700 modem has AC1600 in its title and says it's dual band (I'm also pretty sure it is just a modem and not a router/modem combo unit as this question was specifically asked and answered about the model on amazon). But most of the modems on newegg do not mention if they are dual band and don't mention an AC number in the modem's title or specs.

Models I've considered on the Cox Certified Modems list:
-Arris SBG6700, AC1600, dual band, 8x4, for $100
-Netgear C6300BD, AC1900, dual band, 24x8, for $50 USED
-TP-Link CR500, AC1200, no dual band info, 16x4, for $130 (this model is 16x4 yet AC1200 while the Arris SBG6700 is 8x4 but has higher AC1600-confusing)
-TP-Link CR700, AC1750, dual band, 16x4, for $155

Models I've considered not on Cox's list but model's listing says is Cox compatible (none of these models have AC numbers nor say whether they're dual band or not):
-TP-Link TC7620, 16x4, for $69
-TP-Link 7610, 8x4, for $40
There's also the Arris SB8200 for $189, 32x8, and DOCSIS 3.1, but I hope I don't need something with this high of specs and this expensive (I thought after choosing my router that the modem would be cheaper).

It'd be great if someone can help me with these questions. The ultimate question is can someone recommend a modem at the best price, preferably new, that won't bottleneck the speeds of the Trendnet AC2600 TEW-827DRU router (I ultimately don't understand the specs I need of the modem)?

Also, pseudo random question, why do BOTH routers and modems have ethernet LAN ports? Do they serve the exact same purpose?

Thanks very much to anyone who can steer me in the right direction, would like to have wifi in my house soon, just need to buy the dang modem now.
 

mindless1

Diamond Member
Aug 11, 2001
8,621
1,685
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It seems like breaking this down into less of a tutorial and more of a specific Q/A might help.
 

sdifox

No Lifer
Sep 30, 2005
98,820
17,299
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Your confusion is a simple one. There are routers and cable modems. There are also combination devices that has router and modem housed in the same box.

Cable modems operate on qam256 modulation, 8 channel downstream, 4 channel upstream is what 8x4 refers to. Each of the channel is good for 38mbps

So 8x4 DOCSIS 3.0 is fine for 100/10 service, as long as your cable internet provider says so. Some insist you get higher channel ones so they can spread the load better.

You connect the coax from the wall to the cable modem and an ethernet cable from the cable modem to your router. Obviously in a combo device you wuold not need to make that ethernet connection between router and modem.
 

mv2devnull

Golden Member
Apr 13, 2010
1,519
154
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I'd go one step further and say that there are:
* cable modems, routers, and wireless access points
* (probably) cable modems that route
* wireless access points that route
* combination of modem, router, and wireless access point

A modem converts cable signal into ethernet signal. Conversion between Coax and Cat[567]. Without "LAN-port" you cannot connect the Cat.

Multiple LAN-ports on a modem ... allows multiple wired devices to be connected to the subnet provided by the ISP (some ISP's generously provide more than one [public] IP for your use). There is a switch chip in the modem that provides more than one port.

Or perhaps the "modem" has modem, router, and switch functions. You connect multiple wired devices to the "LAN ports" of the switch. They are in your "home LAN" subnet. The router is between your home LAN and the ISP's subnet.

There are "no wired ports" access points, but most "routers" have a (~4-port) switch on the "LAN-side". That amount of wired connectivity seems sufficient for "regular consumer". The rest of us buy (a) discrete switch(es) to get everything (wired) hooked up.
 

JackMDS

Elite Member
Super Moderator
Oct 25, 1999
29,529
416
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For instance, the Arris SBG6700 modem has AC1600 in its title and says it's dual band (I'm also pretty sure it is just a modem and not a router/modem combo unit as this question was specifically asked and answered about the model on amazon). But most of the modems on newegg do not mention if they are dual band and don't mention an AC number in the modem's title or specs.

I guess that in this era of Alt Facts and Fake News it is to find the Truth.

But ..

SBG6700-AC
SURFboard® Cable Modem & Wi-Fi® Router

http://www.arris.com/surfboard/products/wi-fi-cable-modems/sbg6700-ac/
http://www.arris.com/surfboard/products/wi-fi-cable-modems/sbg6700-ac/


:cool:
 

razel

Platinum Member
May 14, 2002
2,337
93
101
The best cable modem is the one that supports the highest number of channels available to you. You will have to ask them for your area.

For WiFi routers you have two radios. 2.4G and 5G. AC1200 is pure marketing. You will not get 1200mb/s or 1600mb/s. It's a sum of the two radios. For AC1200 it's 300 at 2.4G and 866 at 5G. Even then maximum lab tests speed is closer to half for 2.4G. Real world is EVEN less as soon as you lose direct line of sight of the WiFi antenna.

I would focus on the 1st paragraph. Maxing out the number of channels available to you. 2nd I would then do the best I can to gigabit wire as many devices as I can. 3rd would be to try and centrally locate your WiFi router when most of your devices spend their time then elevate the router. Treat it like a light.
 

mindless1

Diamond Member
Aug 11, 2001
8,621
1,685
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While individual service areas can vary (including mine which switched owners twice and present owner doesn't even list my package on their website), Cox has a guideline for modem vs speed tier support. It shows 8x4 channel modems are suitable for their 100/10 "Preferred 100" service and that 16x4 modems can do the "Ultimate" 300/30 service tier. If they're getting 300Mb out of 16 channels then at that (minimum of) 20Mb/channel, 8 should easily do 100Mb.

If you want to make sure, call your local Cox office and ask if modem XYZ will give you full 100Mb speed, but they'll probably just look at a list like I linked below. They do seem to me limiting per channel throughput or else a 4x4 channel model would be capable of 100Mb.

It also shows 4x4 channel models on the "Essential" but not "Preferred 100" which suggests the most cost effective modem for you will be an 8x4 channel model, unless you decide to upgrade to their Ultimate 300Mb plan before whatever you choose, dies of old age, then it would make sense to spend a little more for higher throughput (# of channels) than you'd presently need for 100Mb.

Best price for new, meh it depends on what is on sale at any given moment. You also don't mention if your phone service is through your cable co. which can require a modem with that feature (or in theory a box but they would probably require the modem), but otherwise I would suggest one of the most popular modems, looking for a sale on an Arris/Motorola Surfboard SB6141, otherwise take a look at their supported list, shop around and see if the price difference of moving up to a 16x4 which you don't need yet, makes sense because (if) it's not much more expensive.

https://www.cox.com/residential/support/cox-certified-cable-modems.html
 

ftngrave

Junior Member
Dec 19, 2017
2
0
1
Thanks everyone for your responses! I appreciate it. So here's a summary of my answered questions, in case anyone who searches the forum is looking for the same kind of info.

-Are these 8x4 speeds theoretical or actual?

It seems that 38.1 mbps per channel (so 304x152 on 8x4, 608x152 on 16x4) is an actual, real world throughput speed. It’s worth mentioning that it seems that ISPs can limit or control how the speeds work on these channels. The speed of the channels also seems to be affected by how many other users are on the internet at the same time using the same ISP as you, thus reducing your bandwidth (obtained this info from forum at dlsreports.com).

-Is a 8x4 modem not going to bottleneck the speeds I can get (like close to the speeds as tested by pcmag) with the Trendnet AC2600 router? Probably not. Cox recommends 8x4 modems for their 100 mbps plan, while the only possible bottleneck seems to be if a lot of people in one’s area using the same ISP are causing congestion of bandwidth.

-Or do I need a higher channel count like 16x4? Probably not for 100 mbps internet plan, but certainly wouldn’t hurt due to possible congestion in one’s area (16x4 would be more future proof as well).

-Does one's modem also have to be dual band (if so, I don't know how to tell if a lot of modems are dual band as their specs don't say)?

No…routers, not modems, feature the dual band specification.

-Why do a few of the modems have AC numbers (a lot of them don't)? This means they are a modem/router combo unit.

-Why do BOTH routers and modems have ethernet LAN ports? Do they serve the exact same purpose?

It seems that standalone modems don’t have LAN ports; either modem/router combo units or routers do which serve the same purpose.

-The ultimate question is can someone recommend a modem at the best price, preferably new, that won't bottleneck the speeds of the Trendnet AC2600 TEW-827DRU router (I ultimately don't understand the specs I need of the modem)?

I went with the Arris SB6183, it’s 16x4 and not much more than an 8x4 modem.
 

razel

Platinum Member
May 14, 2002
2,337
93
101
Having a cable modem that supports the maximum channels helps you slow down less when things get congested along your lines. There will be more lanes (channels) for your bits to travel across when traffic gets busy which happens often after dinnertime.

Also make sure the modem you buy is approved. They often will have a list and from there you can research the modem they approved that has the most channels.
 

JackMDS

Elite Member
Super Moderator
Oct 25, 1999
29,529
416
126
Modems do not Bottle neck anything because they are the first on line.

Choosing a Modem involves only one factor. Get the Modem that provides all the Bandwidh that it provided to your connection by the ISP.

First step is.
Make sure the modem you buy is approved. They often will have a list and from there you can research the modem they approved that has the most channels.

Which means, log to your ISP Support fine the Modem that is best for and search Amazon and the like for the Best Price.


:cool:
 

Mike64

Platinum Member
Apr 22, 2011
2,108
101
91
For instance, the Arris SBG6700 modem has AC1600 in its title and says it's dual band (I'm also pretty sure it is just a modem and not a router/modem combo unit as this question was specifically asked and answered about the model on amazon).
Even when you can be sure the questions and answers both refer to the same (exact) model or version of a product you're looking at (which often isn't the case), the "answers" to questions on Amazon are unreliable at best. And mostly they're worthless. Most of them can also be answered by 3-5 minutes of independent Web searching, and of course just going straight to the manufacturer's website is usually helpful, too...;)
 
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