I think the Radio Feed upload was part of it.
But sitting there with only two data loggers uploading, she is hooked up to work server, and the TV is streaming. Shouldn't be a heavy load.
I have no idea of any of your configuration questions except it is 32Mb Down and 5 Mb Up. Techs on the phone when I call say S/N is good from what they see. The last configuration I did on the router was tell it to manage the "Whole Home WiFi" A few items showed up after as "Pod" connected and it seemed OK until today.
Browsed a couple threads of forums and saw some criticism of the CPU in this unit. "Just get a real router, better yet a mesh" was one comment.
If the techs checked the S/N ratio then they probably checked the decibels so you should be good there.
QoS is quality of service and it stops a process from hogging all the bandwidth while also trying to make sure those that need it get it reliably. However, sometimes QoS get's wrong and not all routers allow you to tell it which process is a priority to you.
OFDMA is protocol that allows streaming processes to get the bandwidth they need to be effective and stop lockups by sending streaming data only to the port that asked for that stream.
WMM gives your streaming services priority over all other traffic.
So the bottom line is tweaking some or all of these protocols can give better results or sometime worse results.
The reviews talking about the CPU of your current router are pretty telling. A router is nothing more than a computer with a very specific job, and a bad CPU can wreak a lot of havoc.
One piece of advice Modem/Router combos always perform worse than two separate dedicated units (heat buildup, CPU overload, etc)