Almost every argument about which internet provider is best is really an argument about which technology reaches your house. The company name on the bill matters far less than whether the last stretch of wire into your property is glass, coaxial cable or a copper telephone pair. Understanding what each one can and cannot do will tell you more in five minutes than an afternoon of comparing marketing pages.
This guide explains the three wired technologies, what actually limits each of them, and how to decide between them when your address offers a choice.
Fiber: light through glass
A fiber connection carries data as pulses of light along a strand of glass. Light in glass does not suffer the interference, attenuation and crosstalk that plague electrical signals in copper, which means a fiber line can carry enormous capacity over long distances without degrading. If fiber is the obvious answer but you cannot buy it, our explainer on why fiber is not available at your address covers how to tell whether a build is actually coming.
Three properties follow from this, and they are the reasons fiber is the best residential technology available.
Symmetrical speed
Fiber has so much capacity that providers do not need to ration the upstream direction. A fiber plan generally gives you the same speed up as down. On cable and DSL, upload is a small fraction of download. If anybody in your household uploads video, runs cloud backups, hosts video meetings or works with large files, this is the single most consequential difference between the technologies.
Low, stable latency
Latency is the delay before a response begins to arrive, and consistency of latency matters as much as its average. Fiber delivers low latency with very little variation. That is what makes video calls feel natural and competitive gaming feel responsive.
No evening slowdown
Fiber capacity is not shared in the same constrained way as coaxial, so performance at eight in the evening looks much like performance at eight in the morning.
The disadvantage of fiber is simply that it may not exist where you live. Building it requires digging, and the economics favor dense areas. If you can get it, the decision is usually easy.
Cable: coaxial, and the asymmetry problem
Cable internet uses the hybrid fiber-coaxial network originally built for television. Fiber runs to a neighborhood node, and coaxial cable covers the final stretch to homes. The current standard, DOCSIS 3.1, supports gigabit and multi-gigabit downloads, and in practice cable delivers download speeds that are perfectly competitive with fiber.
There are two structural limitations. The first is asymmetry: coaxial spectrum is divided unevenly, and the upstream slice is small. A cable plan advertising a very high download speed will typically offer upload that is a fraction of it. Our guide to download versus upload speed covers when that asymmetry is felt. The second is sharing: the coaxial segment is shared among the homes on your node, so evening congestion can reduce real speeds below the advertised figure.
Neither limitation matters for a household that mostly streams, browses and downloads. Both matter a great deal for a household that uploads. Cable is best understood as an excellent consumption technology and a mediocre production one.
DSL: copper telephone lines
DSL sends data over the same copper pair that carried analog telephone service. Its defining characteristic is that performance degrades with distance from the serving equipment. A home close to the cabinet may see reasonable speeds; a home a couple of miles further along the same route may see a small fraction of that. Two neighbors on the same street can receive genuinely different service.
Upload speeds on DSL are typically very low, often low enough that a single video call struggles. There is no configuration change or router upgrade that fixes this, because the constraint is in the copper itself.
Most major providers have stopped investing in DSL and are either replacing it with fiber or steering customers toward fixed wireless. If DSL is your only wired option, treat it as a stopgap and check the alternatives regularly. Our reviews of CenturyLink and Frontier both cover providers in the middle of exactly this transition.
How to decide
If fiber is available, take it
There is almost no scenario in which a cable plan beats an available fiber plan on merit. The only realistic argument is a short-term promotional price. Compare over three years rather than one, including equipment fees and the post-promotional rate, and the fiber option usually wins outright.
If it is cable versus DSL, take cable
This is rarely close. Cable will be faster in both directions and more consistent.
If it is DSL versus fixed wireless, test the wireless
Modern 5G home internet generally beats legacy DSL comfortably on speed and price, and it does so without a contract. The catch is that it depends on signal quality at your address, so it needs to be tested rather than assumed. We compare the options in cable versus 5G home internet.
What the technology does not decide
Two things are independent of the technology and are often the difference between a good and a bad experience. The first is your Wi-Fi. A gigabit connection delivered to a cheap router in a metal-framed house will feel slow everywhere except next to the router, and no upgrade to the line will fix that. Test over an ethernet cable first, as described in our guide to checking your internet speed properly.
The second is the pricing model. Two providers using the same technology can differ enormously in whether the price stays where it was put. That is a commercial choice, not a technical one, and it is covered in our guide to lowering your monthly bill.
The short version
Choose fiber if you can get it, because symmetrical speed and stable latency are worth more than any headline download number. Choose cable if fiber is unavailable and your household consumes more than it produces. Treat DSL as a last resort among wired options, and if it is all you have, seriously test fixed wireless before renewing. And whatever you choose, check the upload figure, not just the download one — it is the number that most often determines whether a connection feels good or merely fast.
To see how this plays out between specific providers, read AT&T Fiber vs Xfinity and Quantum Fiber vs CenturyLink.