Cannot Reliably Connect Devices Home Internet

uzun, I've unfortunately had a very similar experience. Got my gray router a few days ago and was really excited. Setup was pretty easy, and after connecting the router to my PC with an ethernet cable, I was getting what I considered to be breakneck speeds (around 240 Mbps download) after having to deal with AT&T 12 Mbps DSL the past several years (no fiber in my neighborhood here in Chicago). But while the Internet on my PC works great for the most part, there are random times when I'll click on a link to go to a website (i.e. ESPN.com), and either it won't load it at all (it just hangs) or it'll take way longer than it should to start loading (like 10-20 seconds). Sometimes I'll go to a website and the pictures won't load for several seconds.

I've also connected the router to my Roku TV with an ethernet cable, but when I do an Internet connection test, it usually only averages between 40 and 60 Mbps (while my dad's PC upstairs, connected via wifi, gets 175 Mbps). It also occasionally tells me that I'm not connected at all. Streaming is hit or miss, sometimes it works, sometimes it says I'm not connected to the Internet.

The most frustrating part is when I try to connect my Playstation 5 to the router. I tried it via wifi first, and the connection was just very unreliable, constantly connecting/disconnecting and switching between 2.4G and 5G from one minute to the next. I tried adjusting the settings in the PS5 to make it stay on only 2.4G or 5G, but neither band worked consistently. I thought connecting with an ethernet cable would fix the problem, but even with a wired connection, online play isn't possible because the connection is too flaky and unreliable. I tried connecting with my PS4 as well, and that wouldn't work either.

All these problems I've listed, none of them were a problem with AT&T. It was slow, but reliable. T-Mobile Home Internet has been blazing fast but unreliable. Thankfully I haven't canceled my AT&T Internet yet so I can still use that for gaming for now, but I can't afford two Internet services for long. I called T-Mobile a couple days ago about some of these problems and the lady told me that she would talk to their engineering department and they'd call back in three days or so if they had any solutions. I don't have a phone plan with them either by the way (just Internet), but I don't know if that has anything to do with the router connection problems, probably not.