Have a year max 300kB / s with a 60,000 line and previously 750kB / s with a 6,000 (the latter is OK)?

The speed check and router say that the download at around 2120Mb / s. I changed the automatic TCP adjustment via command prompt. Since my contract was increased from 6,000 to 60,000, my download speed has dropped by more than half. Whether Steam, Netfix, absolutely absolutely no matter what it is there's a total of max 300kB / s what everyone has to share. A game takes days to download and videos usually only go up to 480p on any platform.

Note: Didn't have a PC for a year and used an almost scrap laptop during this, understandably to a very limited extent, so little more than googling for texts.

I changed the automatic TCP adjustment via command prompt.

Never heard of it. What is that good for ^^?

Start a live Linux and do a speed check with it.

There can be almost 1000 reasons and more. Standard of the laptop, every single cable in the house, WLAN or LAN, cable outside the house, and and and.