Question Network 's speed drops so low While using lan

[Mortata]

Heyy guys, I have this problem Where your internet speed is very low when connecting via my computer(Lan) While everything works perfectly through Wlan so I tried everything to solve it and couldnt,However, my internet speed always goes back to the normal speed whenever I connect to internet with a vpn.
I need help asap pls. Even youtube doesnt surpassess 144p.

 

[jsmithepa]

Normally I don't do express service but I can throw this in: A user can monopolize the Internet, when you have relatively low download/upload.

 

[Mortata]

Normally I don't do express service but I can throw this in: A user can monopolize the Internet, when you have relatively low download/upload.

Nope, I am the only one who uses this net.