Why does my TP-Link AC1200 router leave dead zones in Wi-Fi coverage?

Don't try putting your router near your microwave or stuff that broadcasts on 2.4 GHz, that's a guaranteed disaster! What people often forget is that the AC1200's internal antenna needs to be positioned right - try setting one vertical and the other at 45 degrees, it really does change the coverage. If that doesn't make much difference after that, it might just be that this model has its limits in terms of range, but before you write it off completely, also try changing the Wi-Fi channel manually from the admin panel - sometimes you're just on a channel that's saturated by your neighbors and that creates dead spots.

AC1200s aren't bad in themselves - it's mostly a matter of placement and configuration. A lot of people just stick them anywhere (in a corner, tucked away in a cabinet) and wonder why it doesn't work. Wi-Fi signal needs to circulate freely, so try placing your router up high, in the center of your apartment if possible, and not hidden behind a door or in a closet. Thick walls do block it, that's true, but it's normal for all routers, not just AC1200s.

What people really forget about is interference. You mentioned you have dead zones - so have you checked if you can pick up the Wi-Fi signal but it's just slow, or is there nothing at all? Because those two situations need different solutions. If it's just weak, switch your Wi-Fi band (try 5 GHz instead of 2.4 GHz, it's less crowded), or change the channel in your router settings - by default there's often one that clashes with your neighbors'. You can also check in the settings to see if you can boost the transmission power.

If nothing works after that, you could look into a mesh system or a repeater to cover areas far from the router, but first really try positioning it properly and tweaking the settings. Have you at least checked if your firmware is up to date?

Before you buy a new router, try something simple that actually works: reorient your antennas. A lot of people leave them parallel, but one vertical and one horizontal picks up better in all the corners of your place. Otherwise the AC1200 has limited range, so if you've got multiple floors or a big space, you gotta accept there'll be weak spots no matter where you put it.

One thing you could try if you haven't already: the transmission power settings. A lot of TP-Link routers have a "TX Power" or "Transmission Power" option hidden in the advanced settings, usually set to 75-80% by default. Try bumping it up to 100%, it can make a noticeable difference in coverage. While you're at it, also check if you can change the channel width (20 MHz vs 40 MHz on 2.4 GHz) - 20 MHz is slower but it penetrates obstacles better.