you need to put that in perspective
a 300 megabit internet connection is in terms of megabytes is around 37 megabytes, around what you mention
netflix, for 4k content needs 25 megabits per tv or pc, that is 3 megabytes
you can get 4k content form netflinx in apoximately 12 tvs or pc simultaneously
that is quite alot
about upload speeds, some internet service providers will give you 10 to 1, 2 to 1 or 3 to 1
in your case seems that you got 3 to 1, the upload speed is one third of the download speed, that is perfectly normal on most cases
my home connection is 10 megabits per second, that is aroun 1.2 megabytes and perhaps 200 kilobytes for upload, i got 5 to 1 there
i think you are covered there for a good ammount of time