Connectivity Issues

Greetings. I have an Apple TV 4k 3rd generation in my living room. I have fiber internet (1GB/s). The Apple TV is connected via WiFi. My router is in my office, a few rooms away (AT&T supplied router). When I open my Apple TV and go into the apps window, several tiles do not load. When I try to open Netflix, it fails almost consistently. Other apps seem to work just fine, but the issues are most consistent with Netflix and Apple native apps.

I have run a speed test from my cell phone placed immediately adjacent to the Apple TV and am receiving the capped 300mb/s download and strong connections. My wired connection is at 950mb/s plus.

I can browse the internet, play games, watch movies and access all of these apps and services via my laptops, iPads and cell phones just fine in the same area. The Apple TV is the only one that has an issue, and it is consistent.

Is there any diagnoses that I can run through to try and root cause? The Apple TV software is up to date, I have restarted both the router and the Apple TV many times. This is the only device that has this issue, and this is a brand new unit. Interesting bit of information, I had purchased this new Apple TV as my prior generation Apple TV started experiencing the same symptoms, so there is something consistent between the Apple TV and the connection.

Any thoughts? Advice? It is driving us nuts.

Edit: As an additional note, I just logged into my router and it has both 2.4 GHz and 5 GHz frequencies enabled. Looks like virtually all connections are on the 2.4GHz frequency from what I can see. I do not, unfortunately, see an easy way to disable the 5GHz, so unsure if that is a problem.