Does TP-Link have any other ideas that I should try?

I disabled both beamforming and fast roaming, and now the onn. 4K Pro can connect and stay connected for 30 minutes. Edit: after an hour I noticed the WIFI had disconnected again. I connected...

... and the 6 GHz and 2.4/5GHz all have the same name, and I'm using a wired backhaul for each node.

I've got Fast Roaming, Beamforming, and OFDMA/MU-MIMO all Enabled. Another thing I didn't mention, was that I have the Deco system in access point mode.

Model: Deco XE5300(1.0) AXE5300 Tri-Band Mesh Wi-Fi 6E System I found this "onn. 4K Pro" Google TV set top box that I wanted because of it's good specs compared to other Google TV solutions. However,...