Older routers use SU-MIMO (Single User - Multiple Input Multiple Output), which means the router itself can only talk to one wireless device at a time.
With SU-MIMO if the device you are currently on isn't the one talking to the router at that second, it has to wait until the router finishes talking to any devices ahead of it in the queue before getting a turn.
A modern household can easily have more than 10 WiFi devices running at any time, so this can really affect performance, and might partially explain why you aren't getting the full benefit of the internet speed promised by your Internet Service Provider (ISP).
The newer standard is MU-MIMO (Multi User - Multi Input Multiple Output) which lets your router talk to all the wireless devices simultaneously. It can provide a dramatic improvement in speed.
Choppy streaming video and increased buffering can sometimes be attributed to SU-MIMO, especially if there are a large number of connected devices in the home. The greater the number of connected devices in your home, the greater the impact of switching to a MU-MIMO router can be.
MU-MIMO is sometimes referred to as "next-generation AC" or "AC wave 2", but the terms are interchangeable.
If your router is more than 1yr old, or cost less than $200 it probably doesn't support MU-MIMO. You can check your router's specs online or in the manual to see if it uses SU-MIMO or MU-MIMO.
The best bet is to look for a router that specifically states it supports MU-MIMO, Next-Gen AC, or AC Wave 2.
All WiFi devices are compatible with MU-MIMO routers, so you don't have to worry about replacing some of your older gear to make it work with the new standard.
Regardless of what type of devices you have, you should notice a performance improvement in all your WiFi connected systems if you switch to a MU-MIMO router.
MU-MIMO routers are avalable from Qualcomm, Linksys, Asus, and a growing number of other vendors. Currently you can expect to pay about $200 for a regular MU-MIMO router, or more for enhanced multi-unit systems like Luma.
If your router is on the slower side, or you've recently upped your internet speed but aren't seeing the results, you may want to check if your router is MU-MIMO capable. Given the increased capabilities, not getting a MU-MIMO router might be wasting some of the money you spend on your internet connection.
-The Home Geek