probably because your ISP is restricting / throttling your IPV4/IPV6 Compatibility
Probably because
we're just not ready for a streaming future yet.
To give a bit more information on what I did test out with:
I tested in a couple of places. I tested in my home which has Fios gigabit. 4k streams, my streams to Twitch, P2P transfers, hosting my PLEX server etc. have 0 issues. My latency to most servers is more than adequate. In optimal scenarios, like Counter-Strike, my ping never peaks over 5ms. With Project Stream, there was still a noticeable amount of latency in input with it and generally speaking there were very noticeable artifact. It was like watching a decently setup Twitch stream, except you were playing it, if that makes sense.
At work, it was the same scenario. We've got a Cox business line and a Comcast one, both with basically the same speed and result while playing over Project Stream. I didn't really notice any difference over any of the three connections or devices I tested it out with, leading me to believe I was maxing out what it was capable of doing. Blown up on a 4K display, it just isn't going to scale well. On a monitor in front of my face, the compression was "acceptable". I could tell what was going on and react to what was going on, but it wasn't pretty. I feel far more people are going to prefer local hardware for this reason alone.
For me, my biggest issue was latency despite Google saying my connection was "great" or whatever. I'm very sensitive to this kind of thing, so it may have a larger impact on me as it will on other people, but I just don't think this is ready for the masses and don't think it will be for many, many more years. It is certainly an improvement on PSNow and ESPECIALLY OnLive, but when people are demanding high fidelity graphics to meet the specifications of their, now relatively common high resolution displays, it just isn't going to stack up to local hardware.
Another thing to note, which unfortunately was unable to test but feel like it'll be an even bigger issue is playing a multiplayer title. These games are bigger than they ever have been before, but add the server latency in the game you're playing + the lag of other players + the delay going to the device that you're playing on and that's gonna suck pretty hard. That's going to automatically eliminate quite a few people from the big picture Google might have seeing as live titles like Destiny, The Division, large scale multilayer games like PUBG, Fortnite, Apex Legends and fast paced FPS titles like Call of Duty and Battlefield are so huge now.
Optimally, we get two sets of hardware out of this. We get a Google home console and we get a streaming device, but I feel like it'll just be the streaming device.