I built my first computer in two months ago and switched to Shaw internet 150, I was getting around 150Mbps on the new computer at the start, but recently tested my internet with speedtest.net and shawís own internet test and Iím constantly getting 15Mbps.

The computer is connected directly to the modem through Ethernet

I believe it has to do with the computer not the provider side since,
1. My phone connected to the same modem through wifi gets 130Mbps
2. My older laptops which is also using windows 10 can get to 80Mbps(limited by the older hardware) when connected through Ethernet.
(which also means its not bottlenecked by the Ethernet cable)
Motherboard: Z170A Gaming M5, latest bios
have updated all the device drivers
peer to peer download and almost all of the Windows 10 privacy settings are disabled
-Disabling global autotuninglevel as suggested by a post on ghacks
-Disabling firewall
-Resetting the modem
-Uninstalled the most recent cumulative update(but didnít going on to older updates because Iím not sure how Win10 will reverting the updates especially if not in order which they were installed)

Unfortunately non of the above worked
the computer only have a bare amount of software, only the necessary divers, anti-virus(Norton Security), plus the likes of Microsoft Office, Adobe reader, dropbox etc. and a few steam games.
All hardwares are new.

I have seen people saying they have notice the same problem after a certain windows 10 update but was only resolved it by reinstall windows 10 and refuse any future updates (which I wouldnít really want to resort to unless there is no other option since the updates are important for getting security patches)

Plus, since my laptop which also have the latest Windows 10 on it can get better speed, it probably has so do with certain windows 10 settings or the computerís hardware, or could it be something else? Any one know what might be the cause of this?