Improving Comcast modem signal

Our internet service is Xfinity/Comcast or Verizon. Currently I have Comcast service and use their modem because I had trouble with Netgear modem compatibility with Comcast. The problem is that the Comcast modem doesn’t allow LPS. I don’t know about the Verizon modem. So, for people with modem tweaking experience, any suggestions that will make a notable improvement?

The modem is connected via house Ethernet cable to EtherRegen in my listening room, which is connected to Lumin X1 streamer via fiber optic listening room.


LPS? Linear Power Supply?

Are you loosing packets? If your not dropping the signal, not loosing packets, what is it your looking for?

I went from Cat 5 to Cat 8 that was an eye opener. I use Comcast and their router with the noisy power supply. I did fix their problem they couldn’t.

12.00 GL eliminator.

What in the name of Ceaser’s (the ape’s) ghost is a 12.00 GL eliminator?

It sounds like a dirty dozen laxative.

Fiber optic listening room? Another ghostly puzzle.

You don't have to rent xfinity's xFi Gateway modem, which appears to have its own internal PS.  You can buy your own and quit paying the monthly rental fee.

I use an ARRIS SURFboard modem (not the latest version) that has an external DC power supply, as do many other available modems made by folks like MOTOROLA and NETGEAR.  By purchasing your own modem, you could then use whatever LPS you want.

When looking at the newer modems, I noticed the ARRIS SURFboard SB8200, a  DOCSIS 3.1 Gigabit Cable Modem, also provides dual Gigabit Ethernet ports.  I will be curious to hear from people who know more than I do whether using the second Ethernet port to send a direct signal to my audio server, separate from the rest of my network, would further isolate the server from noise on the network or whether using an Ethernet cable out of my router to a switch offers the same level of isolation - i.e., is there any benefit to having/using a second Ethernet output from the modem?

Sure you can buy your own. Every person I know of that has done that has reverted. When the signal fails (too often) they always blame you and want to bill you for a visit. Who ya crappin’?

I’ve owned in the old analog days, not now no way.

I've had them upgrade mine for the cost of buying one.

That has not been my experience. I’ve used Netgear cable modems with Comcast for many years. I’ve had no issues (one did fail after a few years’ service) and Comcast has corrected its various network issues multiple times without blaming the modem even once.

The rentals equal out the cost of a new ARRIS SURFboard SB8200 in about 10 months.  After that, your modem costs are free. In 16 years, I have purchased 4 new modems (always for purposes of updating) and had zero issues.  Figure an average of a year of rental fees to pay off each of the four modems, and the result has been 10 years without the $14/mo fee, a savings of $1,680

People who live in areas that are susceptible to having problems can always add the additional service fee to pay less for visits.  One caveat is that your self-purchased modem needs to be on their current/approved list, i.e., it cannot be outdated.

Good for youse. Risk taking is what life is all about.

If they have a "range" it is not user selectable. You get whatever is on the truck. Shooting yourself is preferable to going to the "store" around here.

Taking theirs off the bill entails that. The last time I went it was locked up with the door sign stating open while I waited in the car watching too many chumps attempting entry. Go away suckers.

The last time I wanted them to send something (cheap ass TV boxes fail often) they wanted me to pay shipping. ?????

It must be cheaper to send a tech out.

@mitch2 I tried Netgear modem with my Comcast system and I could not get my internet to work. So, I had to go back to the Comcast modem. May be the gigabyte capacity of Netgear conflicted with Comcast?

Easy to use a non rented modem. Unlike fuzzytone’s experience everyone I know who has swapped rental modem out has never gone back. Maybe 10 people so just shows how a small sample size is problematic. 

Modem compatibility is easily verified on Comcast website or even Amazon. I currently own a Motorola MB8611 and am on Xfinity ie Comcast cable. Much easier to swap out and get working than before. All done online via their app. Oh, don’t buy a refurb as often those MAC addresses show as still in use and are a real pain to get authorized. 

I recently went through an install of xfinity/comcast.

They provided the xFi modem/router. It worked fine, but had a few drawbacks. First, $14 a month ($168 a year). Second, it’s WIFI coverage wasn’t very good. Third, their firmware does not let you override the router’s default DNS address, which for me, is a big problem as I use a piHole ad-blocker.

I guess another drawback is that it has an integral power supply, and you cannot substitute your own. FWIW, I am very skeptical that a LPS would make any difference whatsoever. Not trying to start a fight, but an LPS will not change the delivery of bits to their destination. If you’re one that is convinced that electronic noise from your network is a problem, you’ve already isolated your streamer/dac from that with the ReGen and fiber optic.

I returned the xFi and bought a Netgear modem and router (separates!). At first I wasn’t getting the speed with the new setup that I was previously, but phone call to to xfinity solved that. Their very competent and pleasant phone tech said that it was very common for customers to replace their modem/routers.

I am a Comcast Xfinity user as well. I did not know it is an option to substitute out their suppied cable modem and wifi router. I would love to get rid of that thing and not pay the monthly fee. The wifi is weak on that unit, and they told me I have theoir best one.  I often have to reset it, unplug and replug, at high traffic times.

I'm also a Comcast/Xfinity user and use their modem. Every 18-24 months I get their latest and fastest modem. Over the years it has become very easy to update one, the newest ones even update all your passwords on your smart devices like thermostats and TV's. In the old days you would have to go to each device and reenter the WIFI network and password. Also use their "POD" with the Ethernet connections for streaming via my Bricasti M12. Simple and reliable and no dropouts. 

LPS = Linear Power Supply

GL eliminator. = Ground Loop eliminator. 12.00 dollars US.

Always with hangover attitude. Old Bear with a sore head. fuzztone

Nonoise I expect it.. 

That's right..

Time to feed the chickens


skso, you have any problem with noise and the power supply to your Comcast modem? Everyone I get I have to tinker with to get rid of the GL issues.

Mine are quiet as a mouse now. I put a brick on mine too with a dampening mat between them too.

"And the beat goes on"

"Shooting yourself is preferable to going to the "store" around here." Where on earth do you live? I use to visit El Pueblo in Pittsburg CA. One way in and no way out if you got in trouble.. I'm a blue eyed Anglo! I never had a problem.

Same when I use to work the fields with the locals cutting asparagus, dabbing corn, hoeing tomatoes, picking cherries, cotts and the packing sheds. Late 60s I got along because I worked and paid attention. I kept my mouth shut. I still carry a straight razor.

As for guns they just don't scare me, never have. I do respect them.  A pickup truck is a lot more convincing. I've chased a few through the city park.. My dog loves it..

Pickup truck and a Mauri War Club.. I put on Gaelic War paint there can be a problem.. "fag un benlach" Clear the way.



Shooting yourself is preferable to going to the "store" around here.

You sound a bit frustrated with the local service. I assume Comcast is no longer on your Christmas card list!

I hear a lot about the Ground loop issue. What is the problem it can cause and how can I deal with it?

Their latest modem uses an outboard power supply   It’s white and square. Not sure of model name/number

I believe this is what Xfinity supply as standard these days.

Are there any other current models, or is this it?

That (pictured above) is exactly what was installed when I started my xfinity/comcast service a couple months ago. I mis-remembered that it had an internal power supply. My mistake.

@oldhvymec no noise whatsoever. It's actually on a separate circuit and besides my dedicated listening studio is grounded with a wonderful grounding device. Noise floor is basically non-existent.  

The one that I have has an internal power supply. Sksos, what grounding device are you using?

@chungjh yes my modem/router has the internal power supply. As for the grounding box, since I'm a dealer I don't promote it on this site, feel free to PM me.

Thanks. I don't have any noise now with 93% efficient speakers. No mater where I plug mine in the with an external PS it has a ground loop issue. The only piece of gear that does that. It's less than a year old. Great transfer speeds with Cat 8 from Cat 5. The GL eliminator shut the stupid thing right up. 

I've tried 3 of the neighbors PS too. Same thing. You should hear it with Klipsch 103s they will run you out of the room. Neighbors rig.. GL eliminator fixed it right up.

Thanks Ay..



I've used my own Arris modems with Comcast/Xfinity since 2014.  They work fine.  If there is a problem, Xfinity will say it's your modem every time.  So far, it's never been the modem - instead an Xfinity service problem that is solved on their end within some period of time.  If you need  tech onsite, they might charge for that.  I've spent $325 on 3 modems 7 years (I like to keep them up to date), so even with a tech charge, I would be many $$ ahead.  Currently using an SB8200.  No GL, no LPS.


The Internet and the router are digital signal things. Am I wrong to think they don't introduce noise into the bitstream?

Now if a power supply is near some analog device in your setup, the solution would seem to be putting some distance between them or a similar action.

We never had Comcast. On AT&T and now our superior local ISP, Sonic Fiber, I have used a cheap TP-Link Archer 8 modem. It works fine. AT&T requires its gateway device, so my router was behind it as an access point. Sonic lets customers connect their own router to its ONT gateway.

Comcast is a joke.

I have used Netgear  modems for years, and I can assure you the problem isn’t with them. Last year they, Yfinity, offered me gig speed, only to slow down my connection from about 550mbs to 270. Then they told me that even though they lied about their promise to us, the "package" we had was no longer available, so we’d have to switch to a more expensive plan and live with the slower internet speed. ps, I live in FL, your state may differ in what they allow the cable companies to do to their citizens.

Of course, having dealt with them for decades, I recorded all of my conversations with them, and at the end started to play the earlier promissory recordings back while I was talking with customer service. (An apparent code phrase for taking care of the livestock.)

We cut the cable cord, and they haven’t asked for their boxes back yet, and are charging us less than the price of our now correctly charged 250 speed.

So, how to slay these demons? First, they may insist they be involved with resetting your modem, but you can do that with your modem app or through terminal/web browser…. But you can also do it the best way: Disconnect the cable and all other connections to the router, including power. Depress the power button for 30 seconds with no power connected, doing a clean state reboot, then reconnect the modem and attach the power and turn it on, giving it a minute or so to reboot.

I have found that this always solves any problem that I am financially responsible for.

I hope this helps, regardless of brand.


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@william53b agree 100%. I would go further to say a few choice words. In my area, it is the only option for anything “high speed”. I tried to cut the cord completely a couple of years ago. No avail. I use a Motorola VOIP modem, about as good as it gets based on industry reviews. It’s the easiest solution. I think the Comcast phone system is garbage, and causes a good majority of the issues. Problem is, to “unpackage” the plan, Comcast bends you over without any roses. They limit bandwidth options, or they make it ridiculously expensive to have higher tiered service. The best bet is to use the highest quality cables you can find, optimize the network as a whole as much as possible and hang on. One thing I will say about Comcast, is overall the service is pretty reliable, at least in my area. Rarely is there a full on outage. Speeds that suck at times, but rarely an outage outright.

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Be warned that cable modems are soon to be useless - Verizon is now pushing a white cubed wireless 5G device to feed signals to everything with no cables at all. If this works, and I have no doubt that it does, we luddites using pcs and flip phones will be forced into smartphone land whether we wish to be or not.

@steakster is right.

I misread and answered your question thinking you had an issue with your home router. For a cable modem, it has to be compatible with Comcast and that its mac address must be registered with them.

I had done the same thing with an Arris modem I had, before I switched over to business service with Comcast. It is more expensive but business service gets higher priority and better customer service over normal residential service.


"Verizon is now pushing a white cubed wireless 5G device to feed signals to everything with no cables at all."

They've had this for probably two years, although as you say, they've been pushing fixed 5G signals lately.

If you can get Verizon fiber (FIOS), you'll still get faster and more consistent internet than a 5G wireless signal   

Within your house, you'll get a more consistent and faster internet if you used Ethernet instead of WiFi, although it becomes a problem if your house is not already wired for Ethernet.

It's actually on a separate circuit and besides my dedicated listening studio is grounded with a wonderful grounding device. Noise floor is basically non-existent.  

Reading this reminded me of what Mike over at headquarteraudio does:


Some here are gonna go ballistic and say it's overkill but it's just only another perspective to be considered.

All the best,

The pic I posted of the Gateway evaporated.  Here's another.

But now I can't find one with the external power supply that's bundled with it, so this is what an after-market one looks like.

I wonder if it's any better than the original.

FWIW, I spent half an hour this morning in the weeds of reviews on Amazon: Netgear, Motorola, Arris, etc.  And while 85% were happy campers, it seemed like every model had its problems.

Does this mean the Verizon fiber optic system is better than Comcast cable for digital systems? 

I chose to supply my own modem and router with my internet provider. I did place low noise power supplies on both the modem and router--I used iFi power supplies. I didn’t hear a difference when I placed them into the chain. However, I haven’t tried removing them from the chain, and sometimes I only hear a difference after removing something. Also, my total (retail) system cost was about 2k at the time I introduced iFi PSs to the modem and router, and now my total retail system value is about 5k. It’s possible that my system wasn’t resolving enough at the time to hear a difference, but that it might be now.

Like you, I’m looking for upstream solutions to improve sound quality. Here’s the short list of obvious audible upstream improvements I’ve had: DAC upgrade, streamer upgrade, reclocker/master clock, power cables/supplies for the DAC/streamer/reclocker.

I am currently flirting with upsampling, upgrading coax internet cabling to solid core copper coax, and converting the internet coax cable to optical right before the streamer. All of these projects are still TBD. I’m anticipating a nice improvement from converting to optical. My recommendation to you would be to look at optical conversion first, if you haven’t already. Your EtherRegen switch has an optical-in. You don’t necessarily have to run optical through your walls to start. You can start by just converting to optical right before the internet enters the EtherRegen. That way you can play with single-mode and multi-mode SFP transceivers and optical cable to see if one option sounds better than the other. You can also control for media converters (by EtherRegen or Sonore e.g.) and their power supplies. There may also be audio-grade SFP transceivers and optical internet cable I don’t know about.

One thing I’ve thought about, but haven’t yet tried, is breaking down the router into its separate components. As you may know, ISPs will supply consumers with all-in-one modem-routers. Lay people who tinker with their home network will usually get as far as breaking down the AIO modem-router into into separate modem and router. But, the router itself can be broken down into another 3 components: routing, switching, and wifi access points. The benefit to breaking these down is network performance--an old computer with routing software installed is going to outperform an off-the-self router from Best Buy--and components can be upgraded separately. Now that consumer mesh router systems are starting to cost upwards of $700, separating out routing from access point management might make sense from a cost perspective too. Anyway, I don’t know of any audiophiles exploring possible sound quality improvements with commercial-grade or DYI networking solutions. But you could create an amazing home network in the process at least. 

I have just started to play with Roon Cores/music servers. It seems to me that in as far as the a music stream passes through a router, access point, or switch, that those components may audibly affect the stream. 

OMG, Keep bitching about Comcast and Xfinity. I live in the real boondocks. only internet is satellite. Hughesnet has to be the worst. I run out of "fast" internet in 2 weeks. Paying $190. per month for internet only. Dish network is another $160. per month. Country people are getting SCREWED!!!!



It is extremely unlikely that a PC, even one of the fastest ones, will ever outperform a well designed modem/router.  Those devices employ special purpose hardware which utilize TCAM lookups at hardware speeds and encrypt/decrypt hardware, which no PC is ever likely to match, unless the said PCs also have them, which i have not seen any of yet. 

@chungjh iFi has product that fits between a power supply and component: DC iPurifier2. Site says that it supports "5-24v DC (up to 3.5A, 84W)." I might try it for myself. It's already pretty affordable by HiFi standards, but if you don't like the results when using it with your router, you can always place it on another component where it has a greater benefit. I'm considering trying it for myself. iFi even advertises using it with a low noise power supply. Might be worth a shot 



I understand where you are coming from. Regardless, in most enterprise level (and hi end) home routers and switches, CPU speed does not matter that much. CPU maintains the ’control plane’ and programs the specialized switching hardware. Once that is done, CPU is not even involved in the switching. İt gets out of the way and lets the hw do the packet forwarding. So the CPU speed by itself is not that significant.

The speed limits you are experiencing are 99% of the time, the limitations of your service provider and not due to your home router. İt is extremely unlikely that your PC will saturate a hi end home router, especially if you are using a wired connection  

I had a 600 mbit residential service which i upgraded to a 200 mbit business service and i now get much better performance. It had nothing to do with my home router but all due to the change in service by Comcast.

Guys, I have read most of the posts on this thread and I can relate to many of the problems that have been mentioned.  In a short phrase:  COMCAST SUCKS.  And in my case there is no alternative, AND they know it.

The only reason to put this out is to suggest that only government action can change a company like comcast. They have no real competition in many areas, they are arrogant, they do not care how difficult it is to even ask them a question or report a problem. The service and equipment that I used to get with comcast was better five years ago than it is now and the cost is higher. To top it off, every service company is hiding behind COVID as an excuse for poor customer relations. In most cases only the owner of a new home with FO to the house has a chance of improved service; the rest of us are SOL with GOV help.