At home I have 70mb speeds (cable) to stadia. Connection was horrible after 6pm the first week i got my founders edition (I contacted support and they said it might be because of the increased amount of people playing at that time).
I play only on the chromecast ultra (with wired ethernet).... and now the connection gradually became worse and worse... and now it's so bad that I can't play at all because the stutters and lags are just horrendous.
Is anyone else having similar issues? Really hope I get a fix for this since I paid 200$ to experience "the future of gaming" and now it's just collecting dust because it's unplayable even with a decent internet connection.
Then I'm afraid you need to check with your Internet provided, nothing Google can help with here.
On the off-chance it might be something other than your ISP (as others have suggested), I'd have a go at this quick guide: https://forms.gle/4cb5j1JWrUh1JfdYA
You might stumble upon something unexpected that's been causing you problems?
@Pearly If you are having this issue all around your different method of playing I am 99% sure it is in relation with the quality of your internet service or you are having wifi interferance in your house.
Please try this test and report the result us the result back.