I just added the express in the back corner of one room that wasn’t getting the best speed. Today I ran a cat6 cable to it threw the wall and ceiling to have it wired. No no matter wher I go I have coverage and no matter what I do I can’t get over 400Mbs over Wi-Fi. A lot of my devices are Wi-Fi only and my lap top I’d like much more than that. I pay for 1.2G and I can get that on my hardwired computers but nothing close to that Wi-Fi. I don’t need that speed except I’m one location where I use my laptop. So how can I keep my setup I have now but add a newer router into the mix so I can get faster uploads in one particular area?
Again, WiFi is prone to interference. You will rarely get speeds matching ISP service levels over the air, particularly with AC routers and Access Points. 400Mbps is actually pretty good for WiFi performance. When you really need fast downloads, use wired connections.
Speed is a confusing thing, electrons and data travel just as fast on slow networks as fast networks, physics. The perception of speed is what we tend to measure, and it is a bandwidth question, how much data can pass in a period of time. Think of it like a garden hose, put a kink in the hose and the amount of water that gets through is reduced. The water may travel as fast as before the kink, just less of it gets through so it takes longer to fill a bucket.
When you search networks on a device, does it show several neighbor's networks in the list? If so, you are within range of interference. 2.4Ghz is particularly vulnerable to interference from all kinds of sources, radar, bluetooth, wireless home phones, microwave ovens, etc.
A trick you can try is to name the SSID for 5Ghz different. So, NETWORK and NETWORK5G. They can have the same credentials, just different SSIDs. Now, on devices that can use 5Ghz, learn the 5G SSID, and forget the 2.4Ghx SSID.
Why? Because 2.4Ghz will typically max out at 400-500Mbps, is vulnerable to interference, and devices that can only connect to 2.4 are often low bandwidth devices. 5Ghz, while having shorter range, can deliver 1Gbps or better speeds. Yet devices that "know" both frequencies, or which allow the Access Points to determine which frequency to use will often fall back to 2.4 because the signal may appear stronger. But, the algorithms don't typically consider bandwidth (aka perceived speed). By isolating the two frequencies, devices that can use 5Ghz will use that, leaving more bandwidth on the 2.4Ghz spectrum for the legacy devices. Speeds should be considerably faster, potentially even for 2.4Ghz devices due to less traffic on those frequencies.
The WiFi 6 (802.11ax) tech addresses some of the issues with AC, namely interference. It relies on a bit in the packet header to identify which network Access Point it has an active association with so when packets arrive, a quick analysis can be done to determine if a packet should be ignored. This reduces time spent doing a deeper inspection of packets in older WiFi devices, so it reduces bottlenecks.
AC is still capable of good speeds, but you sometimes have to tweak things to get the most out of it. Other things can help, adjusting the channels to avoid overlapping frequencies with other network devices for example.
At the end of the day, too much WiFi can be worse than too little. That is why hardwire whenever possible is a good strategy.