When connecting my PC via CAT8 ethernet directly to the powered google fiber dmark in my home, I'm able to measure connection speeds using Google Fiber's online speed test in the upper 980Mbps range for uploads and downloads. Results were nearly identical every time I ran the test. This is more than fine.
When I place the included google nest pro in the physical connection path FiberPOP -> Nest -> PC -- my connection speeds using the same google fiber online speed test drop into the mid 670Mbps range down and just over 9mbps in the upload. These speeds were the fastest speeds across several test including before and after WAP reboots.
I also have a 3 node set of Eero 6 Pro mesh wifi routers. I substituted my Eero's into the connection path just as I illustrated above and found I was able to achieve symmetrical speeds of 947Mbps.
I'm not the first customer to voice this concern on these forums (and others as my google search would reveal).
