Tel-Star Communications, Inc.

Routers are the oft-ignored work horses of the home network. Most people hardly pay any attention to them unless there is a big malfunction, and people may not consider upgrading them any more than they consider upgrading their washing machine.
Unfortunately, this leads to a situation where the important-but-ignored router ends up being a source of degraded internet connection quality and a diminished user experience for everyone on your network. Upgrading to a current generation router is a cheap and effective way to improve your home network in every way: better Wi-Fi range, stronger signal, and better handling of demands modern users put on their network. The last thing you want in the age of Netflix is a router design from the days when Netflix was synonymous with DVD rentals.
First and foremost: are you experiencing frequent symptoms of an under-powered or overwhelmed router? If you can’t get a Wi-Fi signal everywhere in your home (and have considered getting a Wi-Fi extender or a second router), that’s a good indicator you’re a good candidate for an upgrade. If you frequently have network-related congestion issues, like slow web page loading or stuttering video playback, that can’t be chalked up to a slow broadband connection then it’s a good sign that your router isn’t up to the task of serving everyone in your household.
Even if you aren’t noticing problems, you should also consider the age of your router, too–both in terms of the actual age of your physical device and the age of the particular model. You might have bought the router two years ago, but if the model itself is from 5 or more years ago, there’s a good chance that you’re playing with outdated router tech and could benefit greatly from upgrading. If you’re still using a single radio/band Wireless-G router from 2010 or before, for example, you’re essentially using a bicycle when you could be using a spaceship.
Any router that supports newer standards will be, by default, at least a dual-band router. Older standards like 802.11b and 802.11g use the 2.4GHz band. Newer standards like 802.11ac use the 5GHz band (and some premium routers include two 5GHz bands, a little network magic trick that relies on using two distinct chunks of the 5GHz spectrum). At the bare minimum you’ll benefit from having one band for your older gear and one band for your newer gear that can support 5GHz communication (even if you don’t have any 5GHz stuff yet you’ll still have a nice wide open space for it when you upgrade).
What causes this network congestion everyone complains about? While you can contribute to it simply by having tons of Wi-Fi devices on your network there are also external factors at play. The 2.4GHZ band is chock full of stuff. Not only do many of the communication channels in the 2.4GHz spectrum used by routers overlap each other, but the same chunk of the radio spectrum is used by many cordless phones, baby monitors, wireless security devices, and more. Decreasing the load on your 2.4GHz network and putting some of it on the 5GHz network goes along way towards alleviating congestion problems.

*Originally posted by howtogeek.com